Grenade sniping
From Halopedia, the Halo wiki
Grenade Sniping is a trick done in Halo: Combat Evolved. Have the Infinite Grenades option turned on and chose a level like Longest and climb up a ladder to a ledge. Then, keep throwing grenades everywhere nonstop. This makes you a hard target to get to, unless another player has a sniper rifle or another long range weapon.
