I'm a sucker for prank videos so 2 of my favorites are:
BigDawsTv and Vitalyzdtv
Big Daws is a more light hearted prankster, Vitaly is kinda offensive and known for trying to pick up girls, both equally funny.
Screen Junkies is another good one. You have to check out the Honest Trailer series of videos.

So who do you guys follow or watch?