When Pigs Fly – Meaning, Origin and Usage

Would you like to say that the odds of something happening are unlikely or impossible?  The saying ‘when pigs fly’ is a common figurative English expression that is used to say just that. This post unpacks the meaning, origin, and correct use of the saying.


The phrase ‘when pigs fly’ is a figurative saying that is mostly used in the English language, although it is also translate as a direct phrase to some others.

‘When pigs fly’ is used to refer to something that is unlikely or impossible.

The phrase is often used to compare two things, or said as a statement or a response to one thing.

Common use of ‘when pigs fly’ sees it used as a statement. ‘When pigs fly’ can also be used as a response, or phrased as a humorous question in response to something (e.g. when pigs fly?’).

The phrase implies impossibility by comparing whatever is meant to the impossible event of flying pigs.

There are several ways to use the phrase, including to say ‘when pigs take flight’ instead. This will still give a valid form of the expression.

Not used in the negative form, as it would give an invalid version of the phrase.

Many other impossible comparisons such as ‘when pigs fly’ exist in the English language, including to say ‘when horses talk’.

Example Usage

“I left him because I wasn’t going to shave my armpits for any man. If you want to know when I’m going to shave my armpits for someone, I’ll shave my damn armpits when pigs fly.”

“The day someone on the planet considers pineapple on a pizza to be acceptable, it’s going to be on the day when pigs fly.”

“I told him that I was going to spend a day with his mother at the zoo when pigs fly, and then I sent him the divorce letter.”’

“I don’t drink coffee, and the day that I tell you I would like to go to Starbucks for a latte is probably the day when pigs will fly.”


The origin of the phrase ‘when pigs fly’ is assumed by most online language resources to be from Scottish or German, as there are direct forms of this phrase in both languages.

Most language resources accept that the origin of the phrase is difficult to track down, and they are not sure which uses of the phrase would have occurred first.

According to what is known about the phrase, the expression ‘when pigs fly’ has carried the same meaning since the early uses of the phrase.

By the 1800s, the saying was already in popular use and common in the English language.

The website Urban Dictionary lists the term from November 2005, even though prior use of the term can be found in media and on the internet.

Phrases Similar to When Pigs Fly

  • When horses talk

Phrases Opposite to When Pigs Fly

  • N/a

What is the Correct Saying?

  • When pigs fly

Ways People May Say When Pigs Fly Incorrectly

There are several ways in which someone can use the phrase ‘when pigs fly’ in the wrong way, or misunderstand the meaning of the saying.

Someone can misunderstand the figurative meaning of the phrase if they have no prior context for its use.

Someone can also misuse the phrase in any negative form, as this is not common use of the saying.

Acceptable Ways to Phrase When Pigs Fly

There are several ways in which the phrase ‘when pigs fly’ can be used in the correct way, usually to compare it to something that is deemed impossible or unlikely to happen by the speaker.

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