[lively music] [speech bubble popping] [playful music] - [Narrator] If I said something was going to happen "when pigs fly," how long might you be waiting?

[dramatic music] - [Kid 1] I'm not sure.

[pigs grunting] - [Kid 2] 30 minutes?

- [Kid 3] I would just stare at that one pig until it started flying.

- [Kid 4] Like, it's never gonna happen.

Like, in your dreams.

[bell dinging] - [Narrator] Well, I hope it wasn't something you were looking forward to because saying "when pigs fly" means it's never gonna happen.

- [Mom] Joh.

[screen whooshing] - [Joh] Oh yeah, mom, I'll clean my room [dramatic music] when pigs fly.

[lively music] - [Narrator] Amazingly, lots of other languages use animals to describe something that will never happen.

[lively French-style music] In French, when translated, they say "when hens have teeth."

[hen teeth dinging] [hen clucking] And in Russian, [screen whooshing] "when the crayfish whistle on the mountain."

[whistle blowing] Both as unlikely to happen as a pig, an animal without wings, has to fly.

[pig crashing] - [Pig] So close.

[pig grunting] - [Narrator] To be honest, it isn't totally clear why we say "when pigs fly."

[screen whooshing] [pig graphic popping] One idea is that long ago, farmers used to transport pigs in small rafts on rivers.

And if it was really foggy, it's possible people thought... - Why those pigs really look like they're flying.

- I'd believe that when pigs fl-, fly.

Pigs fly.

Hmm, catchy.

[playful music] - [Narrator] But it is clear that we've been saying the saying for a really long time.

[playful music] [date dinging] In 1865 in Louis Carroll's "Alice in Wonderland," the character of Alice is rudely told she has as much right to think... - [Duchess] as pigs have to fly.

- [Alice] Of course, I can think.

I suppose you'll be a nicer person when pigs fly.

[pig oinking] [screen whooshing] - [Narrator] The first time the saying "when pigs fly" appears in print was way back in 1616 in a dictionary which mentioned an even older Scottish saying... - [Scottish Person] "Pigs fly in the air with their tails forward."

- [Narrator] So it seems people have been saying "when pigs fly" for over 400 years.

[pigs oinking] Now, it's not entirely true that pigs haven't flown.

- [Newsreel Announcer] Great Britain, November 1909.

This little piggy went wee wee wee all the way to the sky with the assistance of this man and the recently invented airplane.

Just a few years ago, it was impossible to imagine people flying, let alone a pig.

- [Narrator] What do you think?

Does that count as a flying pig?

Now, if you'll excuse me, I actually have a plane to catch.

- Attention, passengers aboard Flying Pig Airlines.

Uh, bit of bad news.

Looks like our expected departure time has been slightly delayed to... never.

[passengers sighing] - [Passenger] Every time.

- [Narrator] Well, I guess we probably should have seen that coming.

[playful music] [pig oinking] [upbeat music] [upbeat music continues] [wings popping] [pig falling] [pig crashing]

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