Fake friends can be tricky to spot because they may act like they care, while their actions tell a different story. These idioms about fake friends use short colorful phrases to express big ideas about dishonesty, betrayal, and unreliable behavior. Moreover, vivid idioms can help you recognize counterfeit friendships without relying only on direct descriptions.
Understanding these expressions also improves your language skills and helps you understand natural English in everyday conversations. From fair-weather friends to backstabbers, these useful idioms reveal the real meaning behind words about fake friendship, false support, and betraying trust. They also show how figurative language makes friendship problems easier to describe and remember.
What Is an Idiom?
An idiom is a fixed or established expression whose figurative meaning is different from the literal meaning of its individual words.
For example, “break the ice” does not normally mean physically breaking ice. It means to make people feel more comfortable when they first meet. Likewise, “spill the beans” means to reveal a secret, not to drop a container of beans.
Idioms can be confusing for English learners because the literal words may create a completely different mental picture from the intended meaning. Learning the expression as a whole is usually more useful than translating each word separately.
How Is an Idiom Different From a Metaphor or Simile?
These forms of figurative language are related, but they are not identical.
| Type | What it does | Example |
| Idiom | Uses an established expression with a figurative meaning | “She stabbed me in the back.” |
| Metaphor | Directly describes one thing as another for comparison | “Their friendship was a house of cards.” |
| Simile | Compares two things using like or as | “He was as slippery as a snake.” |
| Literal expression | Says exactly what it means | “He betrayed his friend.” |
The important distinction is that not every creative phrase is an idiom. A writer can invent a fresh metaphor, but an idiom is an established expression recognized and used in English.
Why Use Idioms for Fake Friends?
Idioms can describe fake friendship in ways that ordinary vocabulary sometimes cannot.
They can show the emotional side of betrayal, such as when someone breaks your trust. They can also highlight different types of unreliable behavior. A person who disappears during difficult times is different from someone who pretends to be kind while secretly working against you.
Idioms also make conversations, stories, and personal writing more vivid. Saying that someone is a fair-weather friend creates a stronger image than simply calling that person unreliable. Likewise, saying someone showed their true colors suggests that their real character became visible after being hidden.
For English learners, these expressions also provide useful practice with figurative meaning, vocabulary, context, and everyday English.
Quick List of 20 Idioms
- Fair-Weather Friend
- A Wolf In Sheep’s Clothing
- A Snake In The Grass
- Stab Someone In The Back
- Show Your True Colors
- Sail Under False Colors
- Put On An Act
- Pull The Wool Over Someone’s Eyes
- Throw Someone Under The Bus
- Sell Someone Down The River
- Double-Cross Someone
- Give Someone The Cold Shoulder
- Keep Someone At Arm’s Length
- Read Between The Lines
- Put Up A Front
- Have An Axe To Grind
- Smoke And Mirrors
- Play Someone For A Fool
- Give Someone The Runaround
- Talk The Talk But Not Walk The Walk
Fair-weather friend
Meaning: A fair-weather friend is someone who stays friendly when life is easy but is not dependable when you experience trouble or hardship.
The image comes from treating good weather as a symbol of good times. When the weather changes, the fair-weather friend disappears too.
In a Sentence:
When I lost my job, several people stopped calling, and I realized they had been fair-weather friends.
Other Ways to Say It:
- An unreliable friend
- A friend only in good times
- Someone who disappears when things get difficult
- A conditional friend
Explanation:
This is one of the most direct expressions for fake or unreliable friendship. It does not necessarily mean the person actively betrays you. Instead, it emphasizes lack of loyalty during difficult moments. Cambridge defines a fair-weather friend as someone who is friendly when things are easy but stops being a friend when problems arise.
Best Use: Everyday conversation, personal writing, storytelling, and social situations.
Tone: Casual to neutral, with a clearly negative meaning.
See Also: 20 Idioms for Ears (With Examples)
A wolf in sheep’s clothing
Meaning: A wolf in sheep’s clothing is a person who looks kind, harmless, or friendly but hides harmful intentions.
Literally, the image is impossible: a wolf is disguised as a sheep. Figuratively, the disguise represents a pleasant appearance hiding a threatening character.
In a Sentence:
He seemed like a supportive colleague, but eventually we discovered he was a wolf in sheep’s clothing.
Other Ways to Say It:
- A disguised enemy
- A deceptive person
- Someone who hides their true intentions
- A dangerous person who appears harmless
Explanation:
This expression fits a fake friend particularly well when the person looks trustworthy on the surface but is secretly acting against you. It is stronger than simply saying someone is insincere because it suggests hidden danger or harmful intentions. Cambridge identifies it as an idiom for someone whose friendly appearance hides a bad nature.
Best Use: Storytelling, serious conversation, essays, and dramatic writing.
Tone: Serious and dramatic.
A snake in the grass
Meaning: A snake in the grass is a treacherous person who hides their harmful intentions, especially someone who pretends to be friendly.
The mental image is of a snake hidden in tall grass where you cannot easily see it.
In a Sentence:
I trusted him with private information, only to discover that he was a snake in the grass.
Other Ways to Say It:
- A traitor
- A backstabber
- A hidden enemy
- A deceptive person
Explanation:
This idiom focuses on hidden betrayal. Unlike a person who openly dislikes you, a snake in the grass conceals the danger. Dictionary.com specifically defines the expression as a treacherous person, especially one who pretends to be a friend.
Best Use: Informal conversation, storytelling, and expressive writing.
Tone: Dramatic, figurative, and strongly negative.
Origin Note: The image is old. Dictionary.com connects the expression with the idea of a concealed snake and notes an early association with the Latin poet Virgil.
Stab someone in the back
Meaning: To stab someone in the back means to betray or seriously hurt someone who trusted you.
The expression is not normally literal. The imagined “stab” represents a sudden and painful act of betrayal.
In a Sentence:
I thought we were close, so it hurt when she stabbed me in the back by sharing my private messages.
Other Ways to Say It:
- Betray someone
- Turn against someone
- Act disloyally
- Backstab someone
Explanation:
This is particularly useful when a fake friend does something harmful behind your back. The expression emphasizes broken trust rather than simple disagreement. Cambridge defines it as doing something harmful to someone who trusted you.
Best Use: Everyday conversation, personal messages, storytelling, and informal writing.
Tone: Emotional and direct.
Common Mistake: Do not interpret this expression as an actual physical attack when it appears in ordinary relationship or workplace discussions.
Show your true colors
Meaning: To show your true colors means to reveal your real character, intentions, or attitudes, especially after previously appearing different.
In a Sentence:
She seemed generous at first, but she showed her true colors when I needed her help.
Other Ways to Say It:
- Reveal your real character
- Show what you are really like
- Reveal your intentions
- Let your true nature appear
Explanation:
This expression works well when a fake friend’s behavior eventually exposes what they are really like. It does not always have to be negative, but it often appears when someone’s real character becomes visible after being hidden.
Best Use: Conversation, storytelling, essays, and personal writing.
Tone: Neutral to negative, depending on context.
Common Mistake: The phrase does not mean simply showing your favorite colors or clothing choices. Its meaning is figurative.
Sail under false colors
Meaning: To sail under false colors means to behave deceptively by hiding your true identity, intentions, or purpose.
The expression comes from the old image of ships displaying a misleading flag to disguise their identity.
In a Sentence:
He acted like a loyal friend, but he was sailing under false colors and secretly competing against her.
Other Ways to Say It:
- Pretend to be someone you are not
- Hide your real intentions
- Deceive others
- Misrepresent yourself
Explanation:
This is a more unusual expression than fair-weather friend or stab someone in the back. It is useful when the main idea is deliberate disguise. Dictionary.com defines it as behaving deceptively, while traditional idiom references connect the image with false identifying flags on ships.
Best Use: Creative writing, historical-style writing, serious discussion, and literary contexts.
Tone: Formal, literary, or dramatic.
Context Note: It is less common in casual everyday conversation, so simpler expressions may sound more natural in ordinary speech.
Put on an act
Meaning: To put on an act means to behave falsely or artificially in order to create a particular impression.
In a Sentence:
Her cheerful behavior around me felt forced, as if she were putting on an act.
Other Ways to Say It:
- Pretend
- Put on a performance
- Fake it
- Act falsely
Explanation:
A fake friend may behave warmly because they want something, not because the friendship is genuine. This expression captures that performance of friendliness. Cambridge classifies put on an act as an informal idiom meaning to behave or speak in a false or artificial way.
Best Use: Everyday conversation, dialogue, social situations, and informal writing.
Tone: Casual and critical.
Pull the wool over someone’s eyes
Meaning: To pull the wool over someone’s eyes means to deceive someone so they do not discover the truth.
In a Sentence:
He tried to pull the wool over my eyes by pretending he had never spoken to my former friend.
Other Ways to Say It:
- Deceive someone
- Trick someone
- Fool someone
- Hide the truth from someone
Explanation:
This expression is useful when a fake friend is actively trying to make you believe something untrue. The figurative image suggests covering someone’s eyes so they cannot see what is really happening. Cambridge gives the core meaning as deceiving someone to prevent them from discovering something.
Best Use: Everyday English, informal conversation, storytelling, and humorous writing.
Tone: Informal and slightly playful, even though the situation may be serious.
Common Mistake: Use “pull the wool over someone’s eyes”, not “pull the wool in someone’s eyes.”
Throw someone under the bus
Meaning: To throw someone under the bus means to harm, blame, expose, or abandon someone to protect yourself or gain an advantage.
In a Sentence:
When the manager asked who caused the problem, my so-called friend threw me under the bus to save himself.
Other Ways to Say It:
- Blame someone else
- Sacrifice someone for your own benefit
- Abandon someone
- Betray someone to protect yourself
Explanation:
This idiom is especially useful when a fake friend chooses self-interest over loyalty. It can describe workplace situations, group conflicts, or personal relationships. Cambridge labels it informal and explains that it involves harming someone else to gain an advantage for yourself.
Best Use: Informal conversation, workplace stories, social media, and casual writing.
Tone: Informal and strongly negative.
Sell someone down the river
Meaning: To sell someone down the river means to betray or abandon someone by failing to support them as promised, usually for personal advantage.
In a Sentence:
He promised to defend me, but when trouble started, he sold me down the river.
Other Ways to Say It:
- Betray someone
- Abandon someone
- Let someone down badly
- Turn against someone
Explanation:
The expression emphasizes a broken promise followed by betrayal. It is stronger than simply saying someone was unreliable because it suggests that the person put their own interests ahead of yours.
Cambridge describes the idiom as putting someone into a difficult or dangerous situation by failing to act as promised, generally to gain an advantage.
Best Use: Informal conversation, storytelling, and dramatic writing.
Tone: Informal and dramatic.
Common Mistake: Do not use it simply because a friend cancels plans. It usually suggests a more serious act of betrayal or abandonment.
Double-cross someone
Meaning: To double-cross someone means to deceive or betray someone who trusted you, especially when you had an agreement or plan together.
In a Sentence:
They agreed to support each other, but Marcus double-crossed his friend when a better opportunity appeared.
Other Ways to Say It:
- Betray someone
- Cheat someone
- Deceive someone
- Turn against someone
Explanation:
This expression is useful when the betrayal happens after cooperation or an apparent agreement. It has a sharper sense of deliberate dishonesty than the general word disappoint.
Cambridge defines double-cross as deceiving someone for your own advantage and notes its association with dishonest or deceptive cooperation.
Best Use: Informal conversation, fiction, crime stories, and dramatic situations.
Tone: Informal and strongly negative.
Give someone the cold shoulder
Meaning: To give someone the cold shoulder means to intentionally ignore them or treat them in an unfriendly way.
In a Sentence:
After I refused to lend him money, he gave me the cold shoulder for weeks.
Other Ways to Say It:
- Ignore someone
- Snub someone
- Avoid someone
- Treat someone coldly
Explanation:
This idiom describes the withdrawal of friendliness, which can be an important sign of a strained or conditional friendship. It does not automatically mean that someone is fake. People can give the cold shoulder for many reasons, so context matters. Cambridge defines the expression as intentionally ignoring someone or showing no interest in them.
Best Use: Everyday conversation, personal messages, and informal writing.
Tone: Casual and mildly dramatic.
Common Mistake: Do not assume that cold shoulder always means permanent rejection. It can describe temporary unfriendly behavior.
Keep someone at arm’s length
Meaning: To keep someone at arm’s length means to avoid becoming too close, friendly, or emotionally involved with them.
In a Sentence:
After several disappointing experiences, she decided to keep her former friend at arm’s length.
Other Ways to Say It:
- Keep your distance
- Stay emotionally distant
- Avoid getting too close
- Maintain boundaries
Explanation:
This expression is useful from the opposite perspective: instead of describing the fake friend, it describes how you respond to someone you do not fully trust. It can suggest caution without directly accusing the other person of being dishonest.
Cambridge defines it as not allowing someone to become too friendly with you.
Best Use: Everyday conversation, relationship discussions, advice, and personal writing.
Tone: Neutral, cautious, and sometimes serious.
Read between the lines
Meaning: To read between the lines means to look beyond someone’s exact words and understand an implied meaning, feeling, or intention.
In a Sentence:
She said everything was fine, but reading between the lines, I could tell she no longer trusted him.
Other Ways to Say It:
- Look for the hidden meaning
- Read into something
- Notice what is implied
- Understand the unspoken message
Explanation:
This idiom is helpful when a friendship looks fine on the surface but subtle clues suggest otherwise. It does not mean that the other person is definitely fake. Instead, it describes the skill of interpreting what is not directly said.
Cambridge defines it as trying to understand someone’s real feelings or intentions from what they say or write.
Best Use: Conversation, essays, relationship discussions, and analytical writing.
Tone: Neutral and thoughtful.
Common Mistake: Read between the lines does not mean inventing a hidden meaning whenever you disagree with someone. The surrounding evidence still matters.
Put up a front
Meaning: To put up a front means to behave in a way that hides your real feelings, intentions, or character.
In a Sentence:
He put up a friendly front whenever we were together, but his private messages told a different story.
Other Ways to Say It:
- Pretend
- Hide your real feelings
- Maintain a false appearance
- Put on a facade
Explanation:
The word front creates the image of a visible surface that hides what lies behind it. For fake friendship, it can describe false warmth, forced kindness, or a carefully maintained appearance.
Cambridge explains put up a front as behaving in a particular way to hide real feelings or intentions.
Best Use: Personal writing, storytelling, essays, and serious conversation.
Tone: Neutral to serious.
Common Mistake: A front does not always mean deliberate dishonesty. Someone may put up a front to hide sadness, fear, or vulnerability rather than to deceive another person.
Have an axe to grind
Meaning: To have an axe to grind means to have a personal reason, interest, grievance, or strong opinion that influences what you do or say.
In a Sentence:
I wondered whether my supposed friend had an axe to grind when he kept criticizing every decision I made.
Other Ways to Say It:
- Have a personal motive
- Have a hidden interest
- Have a grievance
- Have a personal agenda
Explanation:
This idiom does not specifically mean “fake friend.” Instead, it helps describe someone whose behavior may be influenced by a personal motive or unresolved grievance. That makes it useful when you suspect a person’s friendliness has another purpose.
Cambridge defines the expression as having a strong personal opinion or selfish reason that influences your actions.
Best Use: Essays, discussions, analysis, and thoughtful conversation.
Tone: Neutral to critical.
Context Note: This expression is often about motivation, not necessarily betrayal. Do not use it as a direct synonym for fake friend.
Smoke and mirrors
Meaning: Smoke and mirrors describes deceptive appearances, misleading information, or tricks designed to make something seem true when it is not.
In a Sentence:
His constant compliments were just smoke and mirrors; what mattered was how he treated people when nobody was watching.
Other Ways to Say It:
- Deception
- A false appearance
- Misleading behavior
- A distraction from the truth
Explanation:
The image comes from theatrical illusions in which smoke, mirrors, and visual tricks can hide what is really happening. In friendship, the expression can describe a convincing surface that distracts you from unpleasant reality.
Cambridge defines smoke and mirrors as something intended to make people believe something is being done or is true when it is not.
Best Use: Creative writing, essays, commentary, and figurative descriptions.
Tone: Figurative, critical, and sometimes humorous.
Common Mistake: Smoke and mirrors usually describes a deceptive presentation or situation, rather than directly naming a person.
Play someone for a fool
Meaning: To play someone for a fool means to deceive or manipulate someone because you think they are naive or easy to trick.
In a Sentence:
Don’t play me for a fool just because I gave you another chance.
Other Ways to Say It:
- Take someone for a fool
- Trick someone
- Manipulate someone
- Treat someone as if they are naive
Explanation:
This expression is especially useful when a fake friend repeatedly assumes you will believe their excuses or tolerate their behavior. It carries a personal and confrontational feeling.
Collins defines the expression as deceiving someone and using them for your own advantage.
Best Use: Dialogue, personal messages, arguments, and informal conversation.
Tone: Direct, emotional, and confrontational.
Common Mistake: Do not confuse play someone for a fool with make a fool of yourself. The first focuses on someone deliberately treating another person as easy to deceive.
Give someone the runaround
Meaning: To give someone the runaround means to avoid giving a clear answer, useful information, or straightforward help.
In a Sentence:
Every time I asked my friend why she had shared the secret, she gave me the runaround.
Other Ways to Say It:
- Evade the question
- Dodge the issue
- Give vague answers
- Mislead someone
Explanation:
This expression is useful when a fake friend refuses to be honest. Instead of openly admitting what happened, they may change the subject, make excuses, or send you in circles.
Collins explains that giving someone the runaround involves deliberately withholding information or trying to mislead or confuse them.
Best Use: Everyday conversation, workplace situations, complaints, and personal stories.
Tone: Informal and mildly critical.
Common Mistake: It does not simply mean that someone is busy. The expression normally suggests evasion or unhelpful behavior.
Talk the talk but not walk the walk
Meaning: If someone talks the talk but does not walk the walk, they say the right things but fail to act in a way that matches their words.
In a Sentence:
He always talked about loyalty, but when I needed support, he didn’t walk the walk.
Other Ways to Say It:
- Say one thing and do another
- Fail to practice what you preach
- Make promises without acting
- Be all talk and no action
Explanation:
This idiom is particularly useful for fake friends who claim to care but fail to behave like friends. It highlights the gap between words and actions rather than focusing on one specific betrayal.
Cambridge identifies talk the talk … walk the walk as an informal idiom for someone whose actions do not agree with their words.
Best Use: Everyday conversation, essays, social commentary, and personal writing.
Tone: Informal, critical, and sometimes humorous.
Common Mistake: The expression is usually used contrastively: someone may talk the talk, but the problem is that they do not walk the walk.
Exercise: Practice Using Idioms
Choose the best answer for each question.
What does “fair-weather friend” mean?
A. A friend who loves outdoor activities
B. A friend who is dependable only when things are going well
C. A friend who enjoys talking about weather
D. A friend who lives far away
Which idiom describes someone who appears friendly but hides harmful intentions?
A. Give someone the cold shoulder
B. Read between the lines
C. A wolf in sheep’s clothing
D. Keep someone at arm’s length
If someone “stabbed you in the back,” what happened?
A. They physically attacked you
B. They gave you medical advice
C. They helped you unexpectedly
D. They betrayed or harmed you after you trusted them
What does “show your true colors” mean?
A. Reveal your real character or intentions
B. Change your clothing style
C. Choose a new favorite color
D. Hide your personality
Which expression focuses on deliberately hiding your identity or intentions?
A. Give someone the runaround
B. Sail under false colors
C. Give someone the cold shoulder
D. Talk the talk
Someone who is “putting on an act” is:
A. Exercising
B. Telling a joke
C. Behaving in a false or artificial way
D. Speaking very quietly
What does it mean to “pull the wool over someone’s eyes”?
A. Help someone understand a problem
B. Deceive someone
C. Encourage someone
D. Apologize to someone
A fake friend throws you “under the bus” when they:
A. Invite you to dinner
B. Protect you from criticism
C. Give you useful advice
D. Sacrifice or blame you to benefit themselves
Which idiom most clearly suggests betrayal after a promise of support?
A. Sell someone down the river
B. Read between the lines
C. Put up a front
D. Keep someone at arm’s length
If two people “double-cross” each other, they:
A. Exchange gifts
B. Work honestly together
C. Betray or deceive each other
D. Avoid discussing personal matters
What does “give someone the cold shoulder” mean?
A. Offer someone a cold drink
B. Ignore or treat someone in an unfriendly way
C. Give someone emotional support
D. Ask someone to leave a cold room
If you “keep someone at arm’s length,” you:
A. Avoid becoming too close to them
B. Invite them into your home
C. Tell them everything about yourself
D. Ask them for advice
What does “read between the lines” help you understand?
A. The literal meaning only
B. A person’s handwriting
C. Hidden or implied meaning
D. The length of a document
If someone’s friendliness is “smoke and mirrors,” what does that suggest?
A. Their friendliness is supported by strong evidence
B. Their appearance may be hiding the truth
C. They are physically surrounded by smoke
D. They are trying to entertain you
What does “talk the talk but not walk the walk” describe?
A. Someone who speaks several languages
B. Sombody who talks very quickly
C. Someone who avoids conversation
D. Someone whose actions do not match their words
Answers
- B — A fair-weather friend is dependable during good times but may disappear when difficulties arise.
- C — A wolf in sheep’s clothing appears harmless or friendly while hiding harmful intentions.
- D — To stab someone in the back means to betray or harm someone who trusted you.
- A — Showing your true colors means revealing your genuine character, intentions, or attitudes.
- B — Sailing under false colors means behaving deceptively while hiding your real identity or intentions.
- C — Putting on an act means behaving falsely or artificially to create a particular impression.
- B — Pulling the wool over someone’s eyes means deceiving them so they do not discover the truth.
- D — Throwing someone under the bus means harming or blaming them to gain an advantage for yourself.
- A — Selling someone down the river describes serious betrayal or abandonment after an expected promise of support.
- C — To double-cross someone is to deceive or betray them, especially after cooperation or an agreement.
- B — Giving someone the cold shoulder means intentionally ignoring or treating them in an unfriendly way.
- A — Keeping someone at arm’s length means maintaining emotional or personal distance.
- C — Reading between the lines means understanding something that is implied rather than directly stated.
- B — Smoke and mirrors suggests deceptive appearances or information that hides the real situation.
- D — The expression contrasts what someone says with what they actually do.
FAQs
What is a good idiom for fake friends?
Fair-weather friends describe people who stay close during good times but disappear when life gets hard. For betrayal, stab someone in the back is a stronger choice.
How do you describe a fake friend in English?
You can use a snake in the grass for someone hiding harmful intentions or a wolf in sheep’s clothing for someone who seems kind but deceives others.
Which idiom describes a friend who betrays you?
Stab someone in the back directly describes betrayal after trust. Double-cross someone also works when someone secretly betrays an agreement or relationship.
What idiom means someone pretends to care?
Put on an act describes someone who behaves falsely to create a certain impression. Talk the talk but not walk the walk fits someone whose actions do not match their words.
Are idioms about fake friends common in everyday English?
Yes, many friendship expressions are common in everyday English, including fair-weather friend, give someone the cold shoulder, and throw someone under the bus. More unusual expressions may suit formal or creative writing better.
Conclusion
fake friends become easier to describe when you understand the right idioms about fake friends for each situation. From fair-weather friends and backstabbers to betrayal, false support, and unreliable behavior, these expressions add clarity and natural feeling to everyday English. Choose each idiom based on its figurative meaning, context, and intended tone to communicate friendship problems with confidence.
