Friday the 13th: Why is it unlucky?

Better stay indoors, folks. It's Friday 13th, the most cursed day in the calendar.
It's Friday the 13th.It's Friday the 13th.
It's Friday the 13th.

Better stay indoors, folks. It's Friday 13th, the most cursed day in the calendar. But where did we get the idea that it's a date when terrible things happen? Friday the 13th is surely just a myth, right? Let's take a look at the evidence.