Plasma Rifle overheat glitch
From Halopedia, the Halo wiki
The Plasma Rifle Overheat Glitch is a glitch that only works on Halo 2.
You will need a Plasma Rifle or Brute Plasma Rifle and any other weapon. First, fire the Plasma Rifle until it overheats. Then quickly switch to your other weapon and then switch back. If done correctly you will be holding the Plasma Rifle up in the air, but this only lasts for a few seconds.
