break a leg
‘Break a leg’ is an old expression from the theatre. It means ‘Good luck’. Before a play actors want to say ‘Good luck’ to each other; but many actors worried that saying ‘Good luck’ would bring *bad* luck… So they started saying things about bad luck, hoping that would bring *good* luck. Break a leg was the expression that became popular. Nowadays you can say break a leg to someone before a sports game, a job interview, an exam… any time you want to wish them luck. It’s a positive, supportive expression (unless you say it with an evil smile…).
A: I’m so nervous! My TOEIC exam is tomorrow!
B: Break a leg! You’ll do great.
In Japan, people often say ‘Ganbatte’ (がんばって) to each other before a challenge. Do you prefer the nuance of ‘ganbatte’ or ‘break a leg / good luck’?