Friday the 13th

Officially, it's called Triskaidekaphobia, or the fear of thirteen:

Triskaidekaphobia ; from the Greek tris meaning "three", kai meaning "and", deka meaning "10" and phobos meaning "fear" or "morbid fear") is fear or avoidance of the number 13. It is also a reason for the 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).

Rico says it was also a bad movie...