Break a Leg!

"It's bad luck to say 'good luck' on opening night
Once it's said, you are dead
You will get the worst reviews
You've ever read!"

-  From The Producers: Book, Lyrics and Music by Mel Brooks

There is a theater superstition that if you wished your actor friends good luck before a performance, it might have the opposite effect, and lead to bad luck. Instead, you should tell them to "break a leg".

The origin of this phrase is obscure. One explanation suggests that after a performance it is customary for actors to go back on stage to take another curtain call, especially if the applause is prolonged. The longer the applause, the more times the actors reappeared to acknowledge the ovation. In the older theaters, the actors waited below the stage, and had to climb the rickety dangerous stairs to get back up, and if one fell, well, one might break a leg.

So if you wanted the actors to perform brilliantly, you might wish them to receive enthusiastic applause. However, returning for each curtain call would increase the risk of falling down the stairs. Therefore, by urging them to break a leg, you indirectly signal that their performance will be a magnificent one, and greatly applauded.

But a word of warning. During our festival of new musicals, Five Foot Broadway, we received so many requests for legs to be broken, that our narrator, Kevin, fell down a hole and suffered bad bruises to his leg, nearly breaking it. And our star performer, Ros, literally fell down the theater stairs and twisted her ankle. Fortunately she did not break her leg, but she needed to be on a wheelchair for the entire performances.