When pigs fly

The phrase "when pigs fly" is an adynaton—a figure of speech so hyperbolic that it describes an impossibility. The implication of such a phrase is that the circumstances in question (the adynaton, and the circumstances to which the adynaton is being applied) will never occur.

"When pigs fly" is an adynaton, a way of saying that something will never happen. The phrase is often used for humorous effect, to scoff at over-ambition. There are numerous variations on the theme; when an individual with a reputation for failure finally succeeds, onlookers may sarcastically claim to see a flying pig. ("Hey look! A flying pig!") Other variations on the phrase include "And pigs will fly", this one in retort to an outlandish statement.

An example occurs in the film The Eagle Has Landed: an Irish secret agent working for the Nazis replies to a German general speaking of Germany's shortly winning World War II, "Pigs may fly, General, but I doubt it!" Later, when the Irishman sees German soldiers parachuting before an attack, he says to himself, "Mother of God! Flying pigs!"

An identical phrase, used to express impossibilities, exists in Romanian, Când o zbura porcul, literally meaning "When the pig shall fly"; an equivalent also implying an animal is La Paștele cailor, literally: "on horses' Easter". Similar phrases in English include "", the Latin expression "to the Greek calends", and "and monkeys might fly out of my butt", popularized in Wayne's World skits and movies. They are examples of adynata. In Finnish, the expression "kun lehmät lentävät" (when cows fly) is used because of its alliteration. In French, the most common expression is "quand les poules auront des dents" (when hens will have teeth).

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