Fifty-degree Banshee fire
From Halopedia, the Halo wiki
The 50 Degree Banshee Fire glitch is available only for Halo: Combat Evolved and Halo: PC.
To perform that glitch, play any level with a Banshee (i.e. Early Assault on the Control Room or Two Betrayals). Use the Banshee and shoot at a tree when it's close to you. All your bullets will barely graze the tree and shoot upwards.
Although this is possible to do with the alternate shot, or Fuel Rod shot, it is not safe because the plasma is controlled by gravity. It sometimes hits the tree and damages the player.
