Infinite Armor Lock glitch
From Halopedia, the Halo wiki
The Infinite Armor Lock glitch is a glitch that can be performed in Halo: Reach. It can be done solo, or in a group, in Forge, and creates an armor lock effect on the user(s) while still allowing them to move, shoot, use other armor abilities, etc. The player is still vulnerable to assassinations, environmental damage (kill balls, drowning, etc.) and EMP bursts.