"Break A Leg "

"Break A Leg" doesn't make sense when you hear someone tell another who are just about to go on a stage or face a challenge. When I heard of this idiom for the first time, I was quite shock. Why would you want someone to break a leg when they are just about to go on a stage. IT did not make any sense to me.

""Break a leg" is an idiom in theatre used to wish a performer "good luck". Well-wishers typically say "Break a leg" to actors and musicians before they go on stage to perform. The origin of the phrase remains obscure.The expression reflects a theatrical superstition in which wishing a person "good luck" is considered bad luck.^[2][3][4] The expression is sometimes used outside the theatre as superstitions and customs travel through other professions and then into common use. Among professional dancers, the traditional saying is not "break a leg," but "merde"" (Wikipedia).
 

^{"Break a leg" is quite useful phrase. It is probably similar to Ganbatte in Japanese but only aprropriate when used when a person is going on a stage for a performance or presentation. If you have a theatric performance, dance performance, musical performance, and presentation coming up, "break a leg".}