If you see someone burst from the doors of a theater, spin around three times, spit over their left shoulder, and shout out a Shakespearean phrase or curse word, it’s likely they just uttered “Macbeth” inside the building and are trying to keep a very famous curse at bay.

As the story goes, saying “Macbeth” in a theater when you’re not rehearsing or performing the play can cause disaster to befall the production. Instead, actors commonly refer to it as “the Bard’s play” or “the Scottish play.”

According to History.com, the curse of Macbeth originated after a string of freak accidents occurred during early performances of Shakespeare’s 1606 play. In the very first show, the actor portraying Lady Macbeth unexpectedly died, and Shakespeare himself had to take over the role. In a later one, an actor stabbed King Duncan with an actual dagger rather than a prop knife, killing him on stage.

Macbeth has continued to cause calamity after calamity throughout its four centuries of existence. Harold Norman died from stab wounds sustained during a fight scene while playing Macbeth in 1947, and there have been several high-profile audience riots at various performances, too—the worst was at New York’s Astor Place Opera House in 1849, when fans of British actor William Charles Macready clashed with those of American actor Edwin Forrest. Twenty-two people died, and more than 100 others were injured.

Since Macbeth has been around for so long and performed so often, it’s not exactly surprising its history contains some tragic moments. But many believe these accidents are the result of a curse actual witches cast on the play when Shakespeare first debuted it.

As the Royal Shakespeare Company explains, Shakespeare really did his research when creating the three witches in Macbeth: “Fillet of a fenny snake,” “eye of newt and toe of frog,” and other lines from the “Song of the Witches” were supposedly taken from “real” witches’ spells from the time. According to legend, a coven of witches decided to punish him for using their magic by cursing his play.

For skeptics, Christopher Eccleston—who played Macbeth in a Royal Shakespeare Company production in 2018—offers a slightly more believable theory about the origin of the curse. In the interview below, he explains how theater companies that were struggling financially would stage Macbeth, a crowd favorite, to guarantee ticket sales. Therefore, saying “Macbeth” in a theater was an admission that things weren’t going well for your company.

[h/t History.com]