Have you ever had a friend who smiled at you but talked about you behind your back?
Maybe someone acted supportive when things were going well, but disappeared when you needed help.
English has many colorful idioms for fake friends that can help you describe these situations naturally.
Idioms are phrases whose meaning is different from the literal meaning of the words.
For example, if someone is a “fair-weather friend,” they are not literally a friend who likes sunny weather.
They are someone who stays around only when life is easy or useful for them.
Imagine telling your friend, “Sarah seemed really nice, but when I lost my job, she stopped answering my messages.
Now I know she was just a fair-weather friend.” That sounds much more natural than simply saying, “Sarah was not a real friend.”
In this guide, you will learn 40+ idioms and expressions about fake friends, betrayal, dishonesty, and two-faced people.
You will also see real-life examples, conversations, cultural notes, mistakes to avoid, and practice exercises.
What Is a Fake Friend?
A fake friend is someone who pretends to care about you but does not genuinely support or respect you.
A fake friend may:
- Talk negatively about you behind your back.
- Use you for personal gain.
- Be friendly only when they need something.
- Feel jealous of your success.
- Disappear when you need support.
- Pretend to support you while secretly hoping you fail.
English speakers use many idioms to describe these behaviors. Some are gentle, while others are quite strong.
🐍 40+ Idioms for Fake Friends and False Friendship
1. A Fair-Weather Friend
A fair-weather friend is someone who stays with you when everything is going well but disappears during difficult times.
“Tom was there when I was successful, but when I lost my job, he vanished. He was just a fair-weather friend.”
This is one of the most useful expressions for describing an unreliable friend.
2. Two-Faced
Someone who is two-faced behaves differently with different people, often pretending to be friendly while secretly criticizing someone.
“Be careful with Lisa. She can be very two-faced.”
Usage: This is common in everyday conversation but can sound quite negative.
3. Backstab Someone
To backstab someone means to betray someone, especially secretly.
“I trusted him with my plans, but he backstabbed me by telling everyone.”
The image is powerful: someone appears friendly while secretly attacking you.
4. Stab Someone in the Back
This expression has a similar meaning to backstab.
“I can’t believe she stabbed me in the back after everything I did for her.”
It is often used when the betrayal feels personal.
5. Talk Behind Someone’s Back
If someone talks behind your back, they say negative things about you when you are not present.
“I heard that Mark has been talking behind my back.”
Mini Dialogue
Emma: “Did you hear what Jake said about me?”
Nina: “Yes. Apparently, he has been talking behind your back.”
Emma: “I thought he was my friend!”
6. Show Your True Colors
When someone shows their true colors, their real personality or intentions become clear.
“She seemed helpful at first, but she showed her true colors when I needed her.”
This idiom can be used for both people and organizations.
7. A Snake in the Grass
A snake in the grass is a person who appears harmless or friendly but is secretly dangerous or dishonest.
“I thought he was on my side, but he was a snake in the grass.”
🐍 Cultural note: Snakes have long been used as symbols of danger or betrayal in many forms of Western storytelling.
8. A Wolf in Sheep’s Clothing
A wolf in sheep’s clothing describes someone who looks harmless but has bad intentions.
“Don’t trust his friendly behavior. He could be a wolf in sheep’s clothing.”
This expression is especially useful when someone’s appearance hides their true character.
9. A Frenemy
A frenemy is someone who acts like a friend but is actually a rival or enemy.
“We used to be close, but now we’re more like frenemies.”
Fun twist: Frenemy combines friend + enemy.
10. Double-Cross Someone
To double-cross someone means to betray someone after making an agreement or pretending to cooperate.
“I trusted him to keep the secret, but he double-crossed me.”
It is often used in stories, business situations, and dramatic conversations.
11. Pull the Wool Over Someone’s Eyes
If someone pulls the wool over your eyes, they deceive you.
“He pretended to be my friend, but he was only using me. He really pulled the wool over my eyes.”
Common mistake: Don’t use this to mean physically covering someone’s eyes. It is about deception.
12. Wear a Mask
To wear a mask means to hide your real feelings, personality, or intentions.
“She was always smiling, but I think she was wearing a mask.”
This expression is often used in emotional or literary writing.
13. Keep Up Appearances
Someone who keeps up appearances tries to make a situation look better or happier than it really is.
“They acted like best friends just to keep up appearances.”
14. Put on an Act
If someone puts on an act, they pretend to be a certain way.
“His kindness was just an act.”
This is useful when someone’s friendly behavior feels fake.
15. Put on a Show
To put on a show means to behave in a way designed to impress or deceive others.
“They acted like close friends in public, but it was all just a show.”
16. All Smiles
Someone who is all smiles appears extremely friendly and cheerful.
“He was all smiles when he needed my help.”
The phrase itself is not always negative. Context can make it sarcastic.
17. Smile to Your Face
If someone smiles to your face but behaves differently elsewhere, their friendliness may be false.
“She smiles to your face but criticizes you later.”
A more natural full expression is often:
“She smiles to your face and talks about you behind your back.”
18. Sing Someone’s Praises
To sing someone’s praises means to praise them enthusiastically.
“He sang my praises in the meeting, but later complained about me.”
This expression can describe genuine praise or, depending on context, suspiciously exaggerated praise.
19. Butter Someone Up
To butter someone up means to praise or flatter someone because you want something from them.
“He only started complimenting me because he wanted a favor.”
Workplace Example
“Don’t let him butter you up. He probably wants you to do his work.”
20. Sweet-Talk Someone
To sweet-talk someone means to use charming or flattering words to persuade them.
“She sweet-talked me into lending her my car.”
It does not automatically mean the person is a fake friend, but it can describe manipulative behavior.
21. Use Someone
If someone uses you, they treats the relationship as a way to get something they want.
“He never called unless he needed something. I felt like he was using me.”
This is not a traditional idiom, but it is one of the most natural expressions for everyday English.
22. Take Advantage of Someone
To take advantage of someone means to unfairly benefit from their kindness, trust, or weakness.
“She knew I would help her, so she took advantage of my kindness.”
23. Have an Ulterior Motive
An ulterior motive is a hidden reason for doing something.
“I wonder if he has an ulterior motive for being so helpful.”
This phrase is useful in both everyday and professional English.
24. Have an Axe to Grind
If someone has an axe to grind, they have a personal reason for criticizing or opposing someone.
“He keeps attacking her ideas because he has an axe to grind.”
This does not necessarily mean someone is a fake friend, but it can explain hidden hostility.
25. Hold a Grudge
To hold a grudge means to remain angry about something that happened in the past.
“She pretends everything is fine, but I think she still holds a grudge.”
26. Have It In for Someone
If someone has it in for you, they seem determined to criticize, hurt, or cause problems for you.
“I don’t know what I did, but my coworker seems to have it in for me.”
27. Give Someone the Cold Shoulder
To give someone the cold shoulder means to deliberately ignore or treat them in an unfriendly way.
“After our argument, she gave me the cold shoulder for weeks.”
A fake friend might suddenly give you the cold shoulder when you stop being useful to them.
28. Turn Your Back on Someone
To turn your back on someone means to abandon or refuse to support them.
“When I needed help, several people turned their backs on me.”
29. Leave Someone in the Lurch
If someone leaves you in the lurch, they abandon you when you need help.
“My friend promised to help me move, but he canceled at the last minute and left me in the lurch.”
30. Let Someone Down
To let someone down means to disappoint someone by failing to help or keep a promise.
“I trusted her to keep my secret, but she let me down.”
This is softer than backstab or betray.
31. Break Someone’s Trust
When someone breaks your trust, they do something that makes you feel you can no longer rely on them.
“Once he shared my private story, he broke my trust.”
32. Betray Someone’s Trust
This is stronger than simply disappointing someone.
“She betrayed my trust by sharing something I told her privately.”
33. Bite the Hand That Feeds You
This idiom means to hurt or criticize someone who helps or supports you.
“He complained about the manager who had given him the job. He’s biting the hand that feeds him.”
It is useful when a person’s behavior seems ungrateful.
34. Don’t Bite the Hand That Feeds You
This is also used as advice.
“Your boss gave you an opportunity, so don’t bite the hand that feeds you.”
Usage warning: This can sound judgmental, so choose it carefully.
35. Play Both Sides
To play both sides means to support two opposing people or groups, often to benefit yourself.
“He tells me one thing and tells Sarah the opposite. He’s playing both sides.”
This expression is especially common in conflicts and workplace situations.
36. Sit on the Fence
Someone who sits on the fence avoids choosing a side.
“When our friends argued, he just sat on the fence.”
This does not always mean someone is fake. Sometimes people genuinely need time to decide.
37. Keep Someone at Arm’s Length
To keep someone at arm’s length means to avoid becoming too close to them.
“After what happened, I decided to keep him at arm’s length.”
This can be a healthy boundary rather than an insult.
38. See Someone for Who They Really Are
This expression means to understand someone’s true character.
“After the argument, I finally saw him for who he really was.”
It is especially natural in personal stories.
39. The Mask Slipped
When the mask slips, someone’s hidden personality or feelings briefly become visible.
“She was polite all evening, but when nobody agreed with her, the mask slipped.”
This expression is vivid and useful in storytelling.
40. The Gloves Are Off
When the gloves are off, people stop pretending to be polite and begin attacking each other openly.
“They had been pretending to be friends for years. Now the gloves are off.”
This is usually used for open conflict rather than simple fake friendship.
41. Throw Someone Under the Bus
To throw someone under the bus means to blame or sacrifice someone else to protect yourself.
“When the project failed, he threw his teammate under the bus.”
This is common in workplace English.
42. Wash Your Hands of Someone
To wash your hands of someone means to stop taking responsibility for or dealing with them.
“I’ve tried to help him several times. I’m washing my hands of the situation.”
It often suggests frustration after repeated problems.
43. Cut Someone Off
To cut someone off means to stop communicating with them or end a relationship.
“After years of drama, she decided to cut him off.”
It is very common in modern conversational English.
44. Draw the Line
To draw the line means to decide that something is unacceptable.
“I can forgive small mistakes, but sharing my private messages is where I draw the line.”
This is especially useful when talking about personal boundaries.
🎭 Idioms by Emotion and Intensity
Not every expression about fake friends has the same emotional strength.
| Intensity | Useful expressions |
|---|---|
| 🟢 Mild | let someone down, keep someone at arm’s length |
| 🟡 Moderate | give someone the cold shoulder, turn your back |
| 🟠 Strong | two-faced, take advantage of someone, play both sides |
| 🔴 Very strong | backstab, stab someone in the back, snake in the grass |
| 🔴 Extreme/dramatic | wolf in sheep’s clothing, double-cross someone |
Learning tip: Start with mild expressions when you are unsure. Strong idioms can sound very personal.
🗣️ Idioms Native Speakers Use in Real Life
Native speakers often do not say:
“My friend is an individual who pretends to care about me but has dishonest intentions.”
That sounds formal and unnatural.
They are more likely to say:
“He’s two-faced.”
Or:
“I realized she was just using me.”
Or:
“He turned his back on me when I needed him.”
Natural English is often short, direct, and emotional.
💼 Fake Friends in the Workplace
Fake friendship is not limited to school or social life. Similar behavior can appear at work.
Consider this conversation:
Alex: “Why did Daniel blame you for the mistake?”
Sam: “I don’t know. I thought we were friends.”
Alex: “He threw you under the bus to protect himself.”
Useful workplace expressions include:
- Throw someone under the bus
- Play both sides
- Butter someone up
- Have an ulterior motive
- Take advantage of someone
- Keep up appearances
- Put on an act
- Double-cross someone
Professional Tip
Be careful with strongly emotional idioms in formal emails.
Instead of writing:
“John is two-faced and keeps throwing people under the bus.”
A professional version might be:
“I have concerns about how responsibility for the issue was communicated.”
The second sentence sounds calmer and more professional.
📚 Idioms in Literature and Storytelling
Idioms about false friendship are powerful in stories because they create vivid images.
Expressions such as “snake in the grass” and “wolf in sheep’s clothing” turn an abstract idea—dishonesty—into a picture readers can imagine.
Compare:
Simple:
“He was secretly dishonest.”
More vivid:
“He was a snake in the grass.”
The second version creates a stronger mental image.
For creative writing, idioms can make dialogue sound more natural. However, too many idioms can make writing feel forced.
😂 Funny Idioms and Creative Twists
English speakers sometimes play with idioms for humor.
For example:
“I thought he was my best friend. Turns out, he was a subscription service—I only heard from him when he needed something.”
Or:
“She wasn’t a fair-weather friend. She was a fair-weather acquaintance with excellent timing.”
These are creative twists, not traditional idioms. They are useful for social media, humor, and casual conversation.
🌍 Mini Cultural Note: Are These Idioms Universal?
Not all cultures describe friendship and betrayal in the same way.
English often uses animals and physical actions to describe human behavior:
- Snake in the grass → hidden danger
- Wolf in sheep’s clothing → hidden bad intentions
- Bite the hand that feeds you → hurt someone who helps you
- Stab someone in the back → secret betrayal
The exact equivalent may be different in another language. So avoid translating an English idiom word-for-word.
📝 How to Use Idioms in Daily Life
In Speaking
Use short expressions in casual conversations:
“He’s so two-faced.”
“She really let me down.”
“I think he’s using you.”
In Writing
Idioms can make personal stories more natural:
“At first, I trusted him completely. Later, I realized he was just using me.”
In Professional English
Use softer expressions:
“I felt disappointed by the way the situation was handled.”
Instead of:
“She stabbed me in the back.”
On Social Media
Idioms work well in short captions:
“True colors always show eventually.”
“Not every smile means friendship.”
⚠️ Common Mistakes Learners Make
Mistake 1: “He is a fair-weather friend” means he likes sunny weather.
❌ Literal interpretation
✅ It means he stays around when life is easy.
Mistake 2: “She backstabbed me in my back.”
❌ Incorrect and repetitive.
✅ “She backstabbed me.”
Or:
✅ “She stabbed me in the back.”
Mistake 3: Using “two-faced” for every unfriendly person
Someone who is simply rude is not necessarily two-faced.
Two-faced suggests that someone behaves differently depending on who is present.
Mistake 4: Using strong idioms in formal situations
Words such as snake in the grass, two-faced, and stabbed me in the back can sound aggressive.
Use them carefully in professional communication.
Mistake 5: Translating idioms word-for-word
English idioms usually have fixed meanings.
Learn:
Pull the wool over someone’s eyes
as one expression meaning to deceive someone, rather than trying to understand it literally.
✍️ Practice: Complete the Sentences
Choose the best expression from the box:
fair-weather friend | two-faced | throw me under the bus | cold shoulder | true colors
- She disappeared as soon as I lost my job. She was a __________.
- He acts friendly around me but criticizes me privately. He’s __________.
- My colleague blamed me for his mistake to protect himself. He tried to __________.
- After our argument, she gave me the __________.
- When the project became difficult, he showed his __________.
Answers
- fair-weather friend
- two-faced
- throw me under the bus
- cold shoulder
- true colors
🎯 Quick Speaking Challenge
Try to describe this situation using three idioms:
Your friend is friendly when you have money. He asks for favors often. When you need help, he disappears. He also talks about you behind your back.
A natural answer could be:
“He’s a fair-weather friend. I think he takes advantage of me, and I’ve heard him talking behind my back.”
Now create your own sentence using:
- two-faced
- snake in the grass
- draw the line
- keep someone at arm’s length
FAQs
Is “fake friend” an idiom?
No. Fake friend is a normal noun phrase, not an idiom. It directly describes someone who pretends to be a friend.
What is the best idiom for a fake friend?
Fair-weather friend is useful when someone stays around only during good times. Two-faced is better when someone acts friendly but behaves differently behind your back.
Are these idioms suitable for IELTS?
Yes, but use them naturally. In IELTS Speaking, a relevant idiom can make your language more varied. Do not force several idioms into one answer. In formal IELTS Writing, simpler and more precise language is usually safer.
Are these expressions formal or informal?
Many are informal, especially two-faced, backstab someone, throw someone under the bus, and frenemy. Expressions such as ulterior motive and take advantage of someone can work in more formal contexts.
Can I use these idioms with native English speakers?
Yes. Most are familiar to native speakers. However, context matters. Calling someone a snake in the grass or two-faced can sound insulting, so use strong expressions when the situation really supports them.
⭐ Fun Fact About English Idioms
English has thousands of idiomatic expressions, and many come from animals, food, sports, nature, and physical actions.
That is why friendship and betrayal can become surprisingly visual:
snake → hidden danger
wolf → hidden threat
back → betrayal
shoulder → emotional rejection
bus → sacrificing someone else
These images help explain why idioms can be so memorable for language learners.
Conclusion
Fake friendships can be confusing because the truth is not always obvious at first.
English gives you many ways to describe these situations, from the gentle “let someone down” to the much stronger “stab someone in the back.”
The key is not to memorize every expression at once. Start with a few useful ones such as fair-weather friend, two-faced, show your true colors, take advantage of someone, and throw someone under the bus.
Then practice them in short conversations and personal examples.
The more naturally you use idioms, the more confident and expressive your English will become. Learn the phrase, understand the emotion, and use it when the situation fits.
Thomas Reed is an experienced English teacher helping students learn with simple, clear lessons.
He focuses on improving speaking, grammar, and confidence through easy daily practice.
