Before going on stage, performers (usually actors) will express support for one another by encouraging their colleagues to “break a leg.”
Actors are a superstitious and cowardly lot. Among the many backstage traditions and sayings, “break a leg” is one of the most prominent. The actual meaning of the phrase is unsurprisingly contrary to its literal interpretation, and as such it stands in for wishing good luck or good performances to one another. Actors tend to be remarkably egotistical, and much of their craft relies on temporarily leaving their conceptions of “self” behind. It is therefore desirable to avoid feeding an actor’s hunger for attention and praise, and so the phrase “break a leg” serves to bring the actor down to earth and approach the stage with an attitude of humility.
Actor who is unfamiliar with stage traditions and theatrical mythology: “Good luck, everybody! We’re going to give an amazing performance. Hey, Julie! You’re gonna be great!”
Actor who knows their goddamn place: “Let’s get out there and do our jobs. Julie, break a leg. You know what? Break two.”
I’ve heard this a lot before. I think it’s interesting that I’ve never met an actor who doesn’t follow it. It’s incredibly taboo in the theatre to wish someone good luck. It’s cool that among this professional community which defies both class and culture, everyone (in America at least) follows this tradition.