Show biz folk have many superstitions - one particularly related to the W.S. play "MacBeth" - it is considered that mentioning the name brings bad luck so the play is always referred to as "The Scottish Play."
An old episode of the PBS TV show from Bitain called "Black Adder" delt with that superstition with hilarious results! If you can find a copy of the episode your students would enjoy it, I'm sure.