Used to describe a person who is really good at Halo 2. The nickname is often used if the person's real name is either hard to remember or hard to pronounce, or if you just don't want to remember their name.
1. My friend Michael Crismon is really good at Halo 2, so everyone calls him "Halo 2 guy"
2. No one really knows his name, so we all just call him "Halo 2 guy"