I started my gaming life in Halo PC, needed a suitable nickname. Thought of Heretic, which you play as in Halo 2, but decided it needed to be a little more unique. So I added 121 to the end of it. It's been my alias for ... ~8 years. Never been known by anything else
Additional info: There is only one other person in the world that uses my nickname. Some guy in Rhode Island. He's got a myspace account, and a few other things.