when a member of the same or opposite sex impedes the attempts of a male to "Get Some Pussy" or "Get Some butt hole". cock blocking can also be considered when one man goes to cock slap a chick and another guy hits the cock down with his hand, hence that guy is gay. ie. the exact opposite of a straight man/cock guider.
"Goddamn it i am soo sick and tired of Bennett cock blocking i totally would have gotten some pussy all up on my dick if he wasn't cock blocking me soo much!"