Friday the 13th is pretty notoriously unlucky and it's origins go back to the 19th century. Like all superstitions, there has to be a reason the idea of this being an unlucky day has perpetuated. I'm sure plenty of bad things have happened on Friday the 13th to be considered such an unlucky day.
And have you ever noticed that most buildings don't have a 13th floor? (If you ever read, Sideways Stories of Wayside School, you'll know it for sure; or if you ever went to a nearby building with more than 13 floors, you'd know that too, of course). (2)
The question is - have you ever had a bad day or something unlucky happen on Friday the 13th?
Well, let's try a bit of a writing prompt.
It's Friday the 13th. And you are a tad paranoid about the day. You've locked yourself into your apartment for the day. The windows are locked. The door is locked. No one else is inside, but you.
You are in the living room, binge watching How I Met Your Mother.
Until you hear a knock.
From behind your closed bedroom door.