countermack
a particular form of cock block in which someone lays down the mack of equal or superior effectiveness to someone else's already existing game-kickage to someone, usually in order to decrease their chances of scoring.
"So I was at this party. Greg was laying down the mack on Robin, but that interfered with my plans since I had been trying to work her for a while. So I laid the countermack on Greg. His game quickly dissolved as I proved him to be a giant mangina"