Triskaidekaphobia is the fear of the number 13, a genuine phobia.
Via Wikipedia - Triskaidekaphobia (from Greek tris meaning "3", kai meaning "and", deka meaning "10" and phobos meaning "fear" or "morbid fear") is fear of the number 13 and avoidance to use it; it is a superstition and related to a specific fear of Friday the 13th, called paraskevidekatriaphobia (from Παρασκευή Paraskevi, Greek for Friday) or friggatriskaidekaphobia (after Frigg, the Norse goddess after whom Friday is named in English). The term was first used by Isador Coriat in Abnormal Psychology.
I am not a huge fan of the Friday the 13th franchise, but I like it ok and its definitely an important addition to horror history as well as a memorable viewing experience(s) in my childhood so I will reluctantly pay it a little homage, sigh.
Well butter my ass and call me a biscuit, that was campy!