Learn English idioms with meanings and examples

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when pigs fly

Used to say something will never happen or is extremely unlikely; often expresses disbelief or sarcasm.

Recorded since the 1600s, based on the absurd image of pigs flying; similar “impossible” sayings existed earlier in European folklore and literature.

Conveys strong disbelief and often sarcasm. Can sound dismissive or rude, so use carefully in formal or sensitive situations; common in casual speech.

  • He says he’ll pay me back tomorrow—yeah, when pigs fly.
  • She’ll apologize first when pigs fly, so don’t hold your breath.
  • They’ll finish the project on time when pigs fly.
  • I’ll believe that rumor when pigs fly.
  • My brother will clean his room without being asked when pigs fly.

Fixed clause introduced by “when.” Often used alone as a sarcastic reply (“When pigs fly.”). Also appears after a statement: “He’ll apologize when pigs fly.” Tense usually future/conditional.

  • never
  • not in a million years
  • no chance
  • not likely
  • when hell freezes over
  • any day now
  • sooner or later
  • it's only a matter of time