There were a group of people really into Slender in one of the dorms last year. They would all gather in one person's room late at night and play the game with the lights off and the volume up.

I went as Slender Man for Halloween three years ago and still had the costume, so naturally I planned a prank with one of the dorm's residents.

There was an outside balcony to the room, so as they were mid-game I opened the door and crept through in full-on Slender Man garb. They all lost it. There's a video of it somewhere.