Artificial Lag Glitch
From Halopedia, the Halo wiki
To do this glitch, start a forge game with at least two people. Have the connection host spawn a shotgun on the ground, then have someone other than him stand near it. Perform the arm glitch with the shotgun, and then have the host let go of it once the person's arms disappear. Next, have the host spawn a plasma pistol. Swap the glitched shotgun out for the plasma pistol. Now, drain the plasma pistol all the way. Once it's drained, have the host spawn a battle rifle, but don't drop it. If you did things right, the person who got glitched should be able to pick up the weapon while a monitor is still holding it. Pick it up and then have the host delete it. Now, have the person who got glitched go into monitor mode. If there is no crosshair, then the glitch worked.
This glitch causes people to slide around instead of walking, and sometimes resembles the effects of a lag switch. People dying out of nowhere, frozen respawn counters, spawning inside of dead bodies, black screens, and sometimes even the ability to go past kill barriers without dying. Sometimes, if there is a delay between pressing up on the d-pad and when entering forge mode, a monitor can appear out of nowhere in front of the player.