Who came up with the expression "When pigs fly!" ?

You have to go back a long way to find the original of this idea. It seems to have been a traditional Scottish proverb, which was first written down in 1586 in an edition of John Withal’s English-Latin dictionary for children. This had an appendix of proverbs rendered into Latin, of which one was the usual form of the proverb in the sixteenth and seventeenth centuries: “pigs fly in the air with their tails forward”. If they did indeed fly, the proverb argues, flying backwards would seem a small extra feat.

Another version is more famous, because it appears in Alice’s Adventures in Wonderland by Lewis Carroll: “I’ve a right to think,” said Alice sharply... “Just about as much right,” said the Duchess, “as pigs have to fly.” Other forms that have appeared at various times include and pigs could fly if they had wings, and pigs may fly, but they are very unlikely birds.

::: Could It be a Trade Mark of the Pink Floyd of the 70's.

"...For the cover artwork, a giant inflatable pig was commissioned to float between the chimney towers of London's Battersea Power Station. However, the wind made the pig balloon difficult to control, and in the end it was necessary to matte a photo of the pig balloon onto the album cover. The pig nevertheless became one of the enduring symbols of Pink Floyd, and inflatable pigs were a staple of the band's live shows from then on..."

Marvinato got it.

The Russians also talk about "when shrimps whistle." And an old poker playing friend recited the ditty "if ifs and buts were candy and nuts, we'd all have a merry Christmas." And the venerable "if wishes were horses then beggars would ride."

well it was from an old time marriage, and one of them said yeah I will do that when pigs fly

you can put the rest of the information in...

because you all must know...

good luck

smile

I did