Quick Meaning
If someone says something will happen "when pigs fly," they mean they don't believe it will happen at all.
"I'll clean my room every day from now on." "Sure. When pigs fly."
It's a humorous, often sarcastic way of saying "that's never happening."
🐷 Wait... Flying Pigs?
WHEN + PIGS + FLY
Possible? ❌ That's exactly the point. ✅
Pigs don't have wings. And that's exactly why this works.
Pigs flying is about as impossible as things get. So saying something will happen "when pigs fly" is really just a funny way of saying: don't hold your breath, because it's not happening — probably never.
Picture the Situation
Someone who's famous for sleeping until noon announces, "Tomorrow I'm waking up at 5 a.m." Their friend, who has heard this before, just smiles and says, "Yeah... when pigs fly."
Nobody actually mentions pigs being unlikely to wake up early. The joke does all the work.
Natural Examples
He said he'd finish the report a week early. Sure, when pigs fly.
When pigs fly, my brother will actually enjoy doing the laundry.
She promised to text back within five minutes. That'll happen when pigs fly.
In a Conversation
Priya: I'm going to start going to the gym every single morning. Sam: When pigs fly. Priya: Rude. But... fair.
When Do You Use It?
Use it when you want to humorously say something is:
- impossible
- extremely unlikely
- not something you expect to happen
Because it's often sarcastic, it can come across as a little harsh. Save it for friendly teasing, not serious or sensitive conversations where someone genuinely needs support.
🇺🇸 🇬🇧 Useful Variation
"When pigs fly" is the more common form in American English. In British English, you're more likely to hear "pigs might fly" (or "pigs may fly"), usually said with the same disbelieving tone: "You? On time? Pigs might fly." Both mean exactly the same thing — only the wording changes.
🧠 Remember It
Picture an actual pig, flapping its little legs, trying to fly through the sky. Until that happens, don't expect the other thing to happen either.
Quick Check
Ravi says, "I'm going to start waking up at 5 a.m. every Sunday." His friend, who knows Ravi sleeps until noon whenever possible, replies, "When pigs fly."
What does the friend mean?
A. Ravi should buy a pig. B. Ravi will probably wake up early. C. The friend doesn't believe Ravi will do it. D. Ravi should travel somewhere.
Answer
C. The friend doesn't believe Ravi will do it. "When pigs fly" signals strong doubt that something will actually happen — here, that Ravi will really wake up early.