Question 1

What does "when pigs fly" mean?

Accepted Answer

Something that will never happen; used to describe an impossible or extremely unlikely event.

Question 2

How do you use "when pigs fly" in a sentence?

Accepted Answer

He'll clean his room when pigs fly.

Question 3

Is "when pigs fly" formal or informal?

Accepted Answer

"when pigs fly" is register-neutral — appropriate in both casual and formal contexts. A humorous expression used sarcastically to dismiss an idea as completely impossible.