Wether you believe in slenderman or not, you've atleast heard of this thing, if you want to jump out of your seat or s***(censoring myself because I haven't really read the CoC for the forums) your pants, I suggest watching marble hornets on youtube(I would link you but I cant).
Warning: it starts off VERY slow but seeing as episodes range from 2mins to 15mins and there are currently 59 episodes with more coming out, it shouldn't be a problem.
Seriously though, give it a try to atleast ep 13