Toï, toï, toï
Before going on stage, artists usually wish each other good luck with the expression "Toï, toï, toï". This replaces the practice of spitting, which was customary in the 18th century.
Others prefer the term "merde" (shit), which refers to the parade of horse-drawn carriages in front of the first theatres and the amount of dung left by the horses. If there was a lot of it, it was a sign that the audience was there and that the show was a success!
Rabbit
Many of the technicians working at the Opéra-Comique came from the seafaring world. That's why some words banned from boats are also banned from the theatre. This is the case with the word "rope", synonymous with death, and the term "rabbit".
Ghost light
When the theatre is closed, it is customary to light a night-light in the middle of the stage. Called "une servante" in french (a maid), it is supposed to ward off any ghosts that might come to haunt the theatre at night. It also allows the technicians to find their way around
Green: a forbidden colour!
At one time, green costumes were dyed using copper oxide or cyanide, toxic products that were extremely dangerous for artists. It is also said that Molière died dressed in green.
Considered a curse, for a long time this colour was no longer worn by actors on stage (which is no longer the case today, and even less so at the Opéra-Comique, which has a natural dyeing workshop).
Yak hair
The Opéra-Comique has a workshop where costumes, accessories and wigs are created. Wigs are often made from natural hair. But to add density... nothing beats yak hair!
"Baignoire" (baths)
The boxes next to the orchestra are called "the baths". Nothing to do with bathing, but they used to be so warm you'd think you were in a hot bath...