Jackals' unlimited Plasma Pistols
From Halopedia, the Halo wiki
Unlimited Plasma Pistols is a trick that can be done in the Halo 2 campaign level, Sacred Icon.
Walkthrough
Play the Sacred Icon level until you find your Jackal or Grunt allies. Destroy the ports the Sentinels come out of so your allies are safe. Grab a Covenant Carbine, if you haven't already got one, and trade it to a Jackal (make sure your other weapon is not a Plasma Pistol or you won't be able to trade with him). Then charge up the Plasma Pistol he just gave you and launch it at his shield. This will bring it down and he will drop the Covenant Carbine and pull out another Plasma Pistol. You can do this over and over and the Jackal will pull out a new Plasma Pistol every time. This trick is sometimes nicknamed, "The Unlimited Plasma Pistol Dispenser".