
Place de l'Opera, Paris. Liebig card, from a series of views of European capital cities, published in late 19th or early 20th century.
“Good luck” = Bad luck
Because of the belief that mischievous spirits lurk within the theatre, determined to ruin a good show, performers will never wish each other “good luck”. Instead, they will say something contradictory as a way to confuse the manic pixies and ideally yield a positive opposite result. Far from simply wishing another performer “bad luck,” which is much too basic for thespians, pre-show sayings include:
“Break a leg”
The overwhelmingly counter-intuitive “break a leg” is often used as well-meaning encouragement before a show. Initially, another way to confuse the theatre spirits, "break a leg" is now considered bad luck in some circles, or as the joke goes:
“Why do actors say break a leg?
Because every play needs a cast!”
“Merde”
The French word for excrement is commonly used as a way of wishing someone good luck in the theatre. Originating in 19th-century Paris, when audiences of the Paris Opéra Ballet would arrive in horse-drawn carriages, an excessive amount of horse manure outside the theatre would indicate a full house. “Merde” became shorthand to wish your fellow dancers a good show and packed audience.