"Break a leg"
A: I have my first piano recital tomorrow!
B: Break a leg! I'm sure you'll do great!
A: My teacher wants me to perform on stage!
B: That's brilliant! Break a leg!
A: Right, I'm going to get changed for my performance.
B: Okay, break a leg!
What does "Break a leg" mean?
We say 'break a leg' to people performing on a stage, which means good luck!
We don't say this to people who are not performing.
It doesn't really mean we want somebody to break their leg!