An ancient Chinese kung fu move which involves a male or a female (hopefully not) whipping out their dick and using it to block a karate chop, hence the name Cock Block. It has the potential to hurt the owner of the dick, but usually ends the fight with the owner of the cock being victorious. This is due to the fact that the other fighter is afraid (usually) of touching the dick, because they don't want to become gay by doing so. If you're fighting a girl.... um i guess you're screwed
Example: Dude 1: Dude I pulled a cock block last night in a fight!
Someone who either intentionally or unintentionally prevents two people from having any kind of intimate contact. Usually done out of jealousy or because of poor perception of social cues.
Methods of cock blocking can include calling one or the other person's cellphone, not leaving them alone, carrying on a pointless conversation, or saying unflattering things about one or both of them.
Example: Did you see Dave and Ashley at the party last night? Joey was being a total cock block to them. He wouldn't let them do anything together.