In a fps, after getting a kill, the player stands on top of the dead body and proceeds to crouch up and down repeatedly, therefore it looks like he is "humping" his opponent. For me, this is best done on Halo 2 (Xbox live) because the person you kill can see that you are "humping" him.
After killing player 2, he did his Victory Hump.
ayon kay j3ss3!!!!! ika-28 ng Hulyo, 2006