Turret Glitch

The Turret Glitch is a glitch you can achieve on the Halo 2 map, Burial Mounds.

Walkthrough
The first step is to get one player up on the tower turret. After this step, toss a plasma grenade up onto the turret, which will kill the operator and break the turret.

Go up to the tower and get close to the turret. It should say "press X to operate turret". Get on the turret and start shooting. Allow the second player come up and look at you from the side. It will appear that the player operating it is holding nothing and the rounds are coming out of nowhere.