When Pigs Fly Meaning: The Idiom for “That Will Never Happen”
When pigs fly means that something is impossible or so unlikely that you do not believe it will ever happen. It is informal, humorous, and often sarcastic.
- “Sure – When Pigs Fly”: What Does This Idiom Mean?
- When to Use “When Pigs Fly” Without Sounding Strange
- When Pigs Fly Examples in a Sentences
- Common Phrases with “When Pigs Fly”
- When Pigs Fly: An Impossible Date Comes True
- A Short Dialogue: “I’ll Believe It When Pigs Fly”
- Small Grammar Traps with “When Pigs Fly”
- “When Pigs Fly” vs “When Hell Freezes Over” and “Over My Dead Body”
- When Pigs Fly Synonyms: Softer and Stronger Alternatives
- Practice Time!
- Quick recap
“Sure – When Pigs Fly”: What Does This Idiom Mean?
A roommate who never cleans says, “I’ll clean the whole apartment tomorrow.” You look at the dishes in the sink and answer, “Sure – when pigs fly.”
The literal picture is funny: pigs do not fly. So if something will happen only “when pigs fly,” it will happen in an impossible world. That is why this when pigs fly idiom is used when you do not believe a promise, prediction, or plan.
So, what does when pigs fly mean in everyday English?
It means:
“I don’t believe that will happen.”
“That’s never going to happen.”
“Yeah, right.”
This idiom is not a neutral way to say “maybe.” It is stronger and more sarcastic. People usually use it as a reaction to something unrealistic.
A quick note on when pigs fly origin: flying pigs have long been used as a funny image of impossibility. For learners, the useful idea is practical: pigs cannot fly, so the event is not expected to happen.
When to Use “When Pigs Fly” Without Sounding Strange
Use when pigs fly when someone says something you find very unrealistic.
A friend who is always late says, “I’ll be early tomorrow.” You reply, “When pigs fly.” The joke works because you both know the pattern: this person is never early.
This idiom sounds natural in casual conversation, friendly teasing, online comments, jokes, and relaxed workplace chat. It often appears after a statement about the future:
“He’ll apologize when pigs fly.”
“She’ll clean her room when pigs fly.”
“That’ll happen when pigs fly.”
It is also common as a short reply:
A: “I’ll finish the whole project tonight.”
B: “Sure, when pigs fly.”
Be careful with serious or emotional topics. If someone says, “Maybe my dad will call me,” answering “when pigs fly” can sound cold. The idiom works best when the topic is light, familiar, or clearly joking.
When Pigs Fly Examples in a Sentences
- He’ll apologize when pigs fly – he still thinks the whole argument was everyone else’s fault.
- I’ll believe it when pigs fly; he’s promised to “start tomorrow” every Monday this year.
- A: “I’m going to stop checking my phone every five minutes.”
B: “Sure, when pigs fly.” - That’ll happen when pigs fly; they can’t even agree on where to have lunch.
- My sister says she’ll clean her room before dinner, but she’ll clean it when pigs fly.
- A: “Maybe the company will cancel all unnecessary meetings.”
B: “When pigs fly. They added three more this week.” - You think rent will go down next year? When pigs fly.
- I’ll give up coffee before work when pigs fly. I can barely speak before my first cup.
- They say the app will have no bugs after the update. I’ll believe that when pigs fly.
- A: “Maybe the airline will give us a free upgrade.”
B: “When pigs fly – they charged me for choosing a seat.”
Common Phrases with “When Pigs Fly”
|
Common phrase |
When it sounds natural |
|
Sure, when pigs fly. |
A quick sarcastic reply when someone makes a promise you do not believe |
|
Yeah, right – when pigs fly. |
Stronger disbelief; often used when the speaker sounds amused or annoyed |
|
I’ll believe it when pigs fly. |
When someone has promised the same thing before and you are not convinced |
|
That’ll happen when pigs fly. |
When an idea sounds completely unrealistic, not just difficult |
|
He’ll do that when pigs fly. |
A flexible pattern for people who almost never do a certain thing |
|
Maybe when pigs fly. |
A joking way to say “probably never” |
|
And pigs might fly. |
A British-style reply after someone says something that sounds too optimistic |
The most useful pattern is:
person/thing + will + verb + when pigs fly
- They’ll lower the prices when pigs fly.
For short replies, use:
Sure / Yeah, right / Maybe – when pigs fly
- A: “I’ll finish all my homework before dinner.”
B: “Sure, when pigs fly.”
When Pigs Fly: An Impossible Date Comes True
A Short Dialogue: “I’ll Believe It When Pigs Fly”
Two classmates are working on a group project. Max promised to make the slides, but he has already missed two deadlines.
A: Has Max sent you the slides yet?
B: No. He says he’ll finish them tonight.
A: Tonight? He said that yesterday.
B: Exactly. I’ll believe it when pigs fly.
A: So we’re making the slides ourselves?
B: Yes. I don’t want to wait and panic tomorrow.
Want more real English like this?
I share practical phrasal verbs, idioms, natural expressions, common mistakes, and short English quizzes on Telegram — in the same clear, everyday style.
Small Grammar Traps with “When Pigs Fly”
Mistake 1: Using the singular form
- Wrong: He’ll help us when pig flies.
- Correct: He’ll help us when pigs fly.
- Why: The fixed idiom uses plural pigs.
Mistake 2: Adding “will” after “when”
- Wrong: I’ll believe him when pigs will fly.
- Correct: I’ll believe him when pigs fly.
- Why: Keep the idiom fixed. Also, English usually uses present simple after when for future meaning.
Mistake 3: Using it as neutral “maybe”
- Wrong: Maybe he’ll come, when pigs fly.
- Correct: He’ll come when pigs fly.
- Why: The idiom does not mean “maybe.” It means “almost certainly never.”
Mistake 4: Using it in formal writing
- Wrong: Your request will be approved when pigs fly.
- Correct: Unfortunately, we are unable to approve your request.
- Why: The idiom is too informal and sarcastic for professional writing.
“When Pigs Fly” vs “When Hell Freezes Over” and “Over My Dead Body”
When hell freezes over
- It also means “never.”
- Difference: It is stronger, harsher, and more emotionally intense than when pigs fly.
- Example: I’ll work for him again when hell freezes over.
Over my dead body
- It also talks about something that will not happen.
- Difference: It means “I will personally stop this,” not simply “that is unlikely.”
- Example: You’re selling Grandma’s house? Over my dead body.
When Pigs Fly Synonyms: Softer and Stronger Alternatives
Never (At no time; not ever)
- Difference: It is neutral and direct, without humor or sarcasm.
- Example: He never arrives early.
Not a chance (There is no real possibility)
- Difference: It is direct and less playful than when pigs fly.
- Example: Not a chance he’ll finish that report tonight.
In your dreams (That will not happen; you are being unrealistic)
- Difference: It is more personal and can sound more mocking.
- Example: You think I’ll lend you my car? In your dreams.
Practice Time!
1.Match the situation to the best reply.
- Your brother always says he will clean his room, but he never does.
- A colleague says the company will stop having long Friday meetings.
- A friend says, “I hope I pass the exam. I studied all week.”
- Someone says, “Maybe the airline will give us a free upgrade.”
A. “You’ve worked hard. I think you have a good chance.”
B. “When pigs fly. They charge extra for everything.”
C. “Sure, when pigs fly.”
D. “That’ll happen when pigs fly.”
2.Choose the sentence that sounds natural.
A. I’ll believe him when pigs will fly.
B. I’ll believe him when pigs fly.
C. I’ll believe him when the pigs fly.
3.Choose the better tone for the situation.
You are writing a formal email to reject a request.
A. Your request will be approved when pigs fly.
B. Unfortunately, we are unable to approve your request.
C. Yeah, right – when pigs fly.
4.Correct the mistakes.
- He’ll apologize when pig flies.
- She’ll cleans her room when pigs fly.
- I’ll believe that when pigs will fly.
5.Choose the best expression.
- You want to sound neutral and professional.
A. That is highly unlikely.
B. When pigs fly. - You want to tease a close friend in a funny way.
A. Sure, when pigs fly.
B. There is little chance of that happening. - You want to sound stronger and more angry than when pigs fly.
A. When hell freezes over.
B. It could happen.
6.Is “when pigs fly” natural here?
- A: “I’ll pay you back tomorrow. I promise.”
B: “You said that last week. I’ll believe it when pigs fly.” - A: “I’m really nervous, but I want to apply to medical school.”
B: “When pigs fly.” - A: “Maybe our boss will cancel the 8 a.m. meeting.”
B: “When pigs fly. He loves early meetings.”
7.Rewrite the sentence with “when pigs fly.”
- I don’t think he will ever say sorry.
- I really don’t believe they will lower the prices.
- I don’t expect my sister to clean her room today.
Answer key:
- 1C, 2D, 3A, 4B; because each reply fits a different situation: Sure, when pigs fly works for friendly teasing, That’ll happen when pigs fly reacts to an unrealistic change, encouragement fits the exam situation, and the airline reply needs a reason for the doubt.
- B; because the fixed idiom is when pigs fly, not when pigs will fly or when the pigs fly.
- B; because a formal email needs neutral, professional language. When pigs fly would sound sarcastic and rude.
- 1 He’ll apologize when pigs fly; 2 She’ll clean her room when pigs fly; 3 I’ll believe that when pigs fly; because the corrections fix plural pigs, the verb after will, and the fixed form when pigs fly.
- 1A, 2A, 3A; because That is highly unlikely sounds neutral and professional, Sure, when pigs fly sounds playful with a close friend, and when hell freezes over is stronger and harsher than when pigs fly.
- 1 natural, 2 not natural, 3 natural; because the idiom fits repeated broken promises and casual disbelief, but it sounds cruel when someone is talking about a serious dream.
- 1 He’ll say sorry when pigs fly; 2 They’ll lower the prices when pigs fly; 3 My sister will clean her room today when pigs fly.”
