The dance world is brimming with superstitions. One of the most common is never to say "good luck" before a show, since everyone knows uttering the phrase is, in fact, very bad luck. Actors say "break a leg" instead. But since that phrase isn't exactly dance-friendly, you and your dance friends probably tell each other "merde" before taking the stage.

According to the Oxford English Dictionary, "merde" is a French exclamation that loosely translates to, er, "poop." So how did dancers end up saying "merde" to each other instead of "good luck"?

To learn more, we spoke to Raymond Lukens, associate emeritus of the American Ballet Theatre National Training Curriculum, and Kelli Rhodes-Stevens, professor of dance at Oklahoma City University. Read on—and the next time you exchange "merdes" with your castmates before a show, you'll know why.