When Pigs Fly Virus 

The 2009 H1N1 Virus which is believed to be made up of Human, Swine, and Bird parts.

The chance of getting this new virus from pigs, birds and people in the spring is about one chance in a million. I think that's why we call it the when pigs fly virus.

When Pigs Fly Virus by Tomicus May 10, 2009

International When Pigs Fly Day 

The first Wednesday of October, farmers around the world climb to the tops of their barns, strap wings on a pig, and throw it down onto a mattress.

Howdy, y’all! Get your porkers ready, because it’s International When Pigs Fly Day!

International When Pigs Fly Day by TheMoosetopian November 1, 2021

That will happen when pigs fly 

A saying that once meant something would never happen. Rendered obsolete with the advent of the police helicopter.

“Cops aint gonna catch us, that will happen when pigs fly!”
“Bro the police helicopter is listening, shut up”

That will happen when pigs fly by Wypipo whisperer August 22, 2019

When pigs can fly 

a phrase often used when something will never happen.

guy: Hey sexy, you me, lunch?

girl: When pigs can fly

When pigs can fly by Diarrhea April 1, 2004