The first thing you need to know is Corpse Humping, straight from Halopedia:
Players started repeatedly crouching over the dead character, resembling the sexual practice of "humping," for derogatory purposes, as the opponent could still see the action while waiting to respawn. This became a common practice in multiplayer games, when a person got Owned, especially if the person killed put up a particularly hard fight. This is a variation of a common practice in internet multiplayer games known as teabagging. Players see this practice as either harmless ribbing to immature taunting.
The Halo Flash Hump Creator allows you to make a customized Corpse hump movie with many options. All humps are stored in the database and are accessible by anyone (Exception: Quick Humps). Purpose of The Halo Flash Hump Creator is to have fun; Create and share your humps and use them like they were electronic greeting cards