Lot of randomness as of late huh?  Anyways, this is based on the Slender Man modern urban legend.  Which in and of itself is a pretty amazing story!  I recommend checking out that link to read up on the history.  But the cliff notes version is that Slender was really formed from the online consensus which congealed into what we have now.  Slender Man is sort of a creepy dude in a suit, sometimes with tentacles, that has no face, very elongated extremities, and can mess you up by looking at him!  “Don’t blink, blink and you’re dead!”  (sorry, had a Dr.Who moment)  But yeah, “legend” has it, if you look at Slender Man, you can have memory loss, pass out, or even die!  This is one of those ‘wins’ for the internet culture.