Welcome to English in a Minute where we teach you all about idioms in American English. You probably have heard someone say, break a leg. Don't worry, she isn't going to break someone's leg. This is an expression that means good luck.
Let's listen to a conversation to find out. I'm so nervous tonight is the first night of the play. Is it? We'll go out there and break a leg.
This phrase began as a way to wish actors good luck. Theater people said that if they wished each other something bad, good might happen. So when you hear break a leg, it really means do well. Also, it can mean to work really hard at something.