When Pigs Fly

In English, we often use the term "when pigs fly" to indicate something that will never happen. It's become so common that we've managed to make flying pigs a pop culture meme. It's not the only way to say it in English, and other languages have their own colorful phrases for "not gonna happen." For example:

Israel "When hair grows on the palm of my hand"

Hungary “When it’s snowing red snowflakes”

Portugal “In the afternoon of Saint Never’s day”

There's more of these at Nautilus , and even a world map showing where more idioms are used.