Infected Brute glitch
From Halopedia, the Halo wiki
The Infected Brute Glitch is a character animation glitch in Halo 2. The glitch sometimes causes Brutes to stand up and enter a battle-ready stance when they are killed. Some players, after witnessing the glitch occur in the Flood-infested High Charity, mistook the glitched Brutes for infected Brutes, resulting in the glitch's rather misleading name.
