A perosn male or female who intentionaly or unentenionally disrupts
(block) somebody from spittin game
, getting someones number,or hooking up.
A.K.A. an annoying ass friend
1.) you could be at a bar talking to the best looking girl in the joint, and this girl might be all about you too, but then your drunk buddy who happens to be a blocker rolls up on the scene and starts falling all over the place, making you look like an asshole and scaring her away. That's a cock blocker.
2.) you might be in a bedroom with a girl about to get a piece and then all of the sudden, your buddy starts banging away at the door for no reason. He just wants to figure out a way for it be as hard as possible for you to get some. That's a cock blocker
examples courtesy of TwanDiggity