When playing the popular XBOX game Halo, after a person kills their opponent he or she should go over to the corpse of his opponent and repeatedly crouch above him. This is known as corpse humping.
Nicholas told me that this is done frequently when playing Halo online. It is a sign of disrespect to ones enemy. He says it is done by him and his friends as a way of celebrating their kill and not so much to disrespect someone. Sometimes people get highly offended when they see that their corpse is being humped. This can lead to shouting matches, nasty texts, or revenge killings (within the game of course).
The act of corpse humping is also sometimes referred to as tea bagging, which is when a person puts his testicles into the open mouth of another person, much like dipping a tea bag into a cup of hot water. The corpse humping mimics that act and that is the reason so many people take offense to it. I asked Nicholas when the first time he learned about corpse humping was and he told me it was the first time he played an online deathmatch in Halo. After being killed, the person that killed him humped his corpse for an extended period of time while taunting Nicholas via text about how he was being teabagged. Nicholas fought fire with fire by killing and teabagging his assailant.
He later started doing it as a way of celebrating an especially challenging duel, but his opponents still frequently take offense to having their corpses humped. I think corpse humping is a way to assert dominance over ones opponent. When a persons corpse is being humped they are completely helpless. They have to wait a certain amount of time for their character to re-spawn (reappear). During this time they are humiliated and helpless. By frequently humping corpses one is making a statement about his superiority and challenging others to take him on.
Here is an example of teabagging in Halo:
Halo 3: The Bag Boy (Machinima)