If you understand French, you might be a little bewildered as to why dancers would say merde to each other before a performance.
The word literally translates to shit.
I know quite a few dancers who use the word and don't quite know why.
Apparently, merde is used among dancers similar to how actors use "break a leg."
There are various stories around the web as to the exact origin.
One version goes: In the early days of ballet, companies used live animals in performances. Whenever one of the animals would drop a load on stage, someone would yell "MERDE!" to let the dancers know to watch out so that they wouldn't slip.
Or: Long ago, when members of high society went to see an event in their horse drawn carriages, the horse crap would pile up in front of the theater. The more successful the show, the bigger the pile -- hence the expression ‘merde’as an expression of ‘good luck’.
Some simply suggest merde is just another reflection of the “it’s bad luck to say ‘good luck’” superstition.
So there you have it.