History of Break a Leg
The idiom "Break a Leg means "good luck". It is often used as a greeting among the actors before they go onstage.
The clear origin of such a term is unclear.
Some said it is adapted from other languages such as Italian and Frence but one of the most reasonable is the following.
In the old time, at the end of performances, the actors would receive tips from the audiences. They would throw money, usually coins, onto the stage if they like the show.
The better the show is the more tips they would receive on the stage.
After the show finishes, the actors would have to, kneel down to pick up those coins.
Humorously, if they kneel up and down until their leg is broken that mean they make a huge amount of tips on that show.
Therefore, it became a humor among the actors to say "break a leg" before go onstage.
Now the time is changed the way people pay tips are also changed but the word is still remained.