On Friday the 13th, the superstitious try to stay clear of black cats, spilling salt, and stopped clocks. Some people even have “paraskevidekatriaphobia,” a fear of the thirteenth day of the month falling on a Friday!

So how did this superstition get started?

How Friday the 13th became a symbol of bad luck

The Last Supper, a sinking ship, and a medieval group of warriors are among the theories.