Break a Leg!

This idiom is very common used before performances to wish good luck! 

It sounds a lot like an irony, I know, but that's the way it is. I found out in the Ancient Greece the people didn't clap after performances. Instead, they stomped and if they stomped for so long, their legs would be broken.

Analizing everything, I don't think people wish to someone to break their leg. They just say it, wishing that the people who watched it, liked. That's what happened with the people who liked the performances in the Ancient Greece, they ended up with broken legs.

Got it?!