Idiom
When pigs fly
When pigs fly means never; people say it about something they are sure will not happen.
How people use it
It is a sarcastic reply to an unlikely idea (he'll clean his room when pigs fly). It is informal and often humorous, but it can sound dismissive. British English more often uses pigs might fly, said after a doubtful claim. When something surprising finally does happen, people sometimes joke that pigs must be flying.
Also said: pigs might fly.
Examples
- My little brother says he will start waking up early, but I think that will happen when pigs fly.
- Sure, the old printer will work on the first try, when pigs fly.
- Grace joked that her cat would learn to fetch when pigs fly.
Where it comes from
Flying pigs have stood for impossible things in English for centuries, with versions of the idea recorded by the 1600s. Lewis Carroll used it in Alice's Adventures in Wonderland (1865), where the Duchess tells Alice she has 'just about as much right' to think 'as pigs have to fly.' Pigs suit the joke because they are heavy and clearly built for the ground.
Check yourself
1. What does a friend mean by saying something will happen when pigs fly?
Answer: It will never happen. When pigs fly is a sarcastic way to say never.
2. Which form is more common in British English?
Answer: Pigs might fly. British speakers often say pigs might fly with the same doubtful, sarcastic meaning.
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