When I was a kid I went with angel of bullets for a while. Oh the cringe... even now... Also shadow or shadowhunter depending on what was available, but at least that was no worse than your average gamertag.
Also had the_truth@... as email for a while... Let's just say I was pretty glad when the world collectively decided to switch from windows mail to hotmail. It was the perfect excuse to forget that emailaccount even existed.
Nowadays I try to go by scatman, and if possible equip myself with a way to play the scatman songs over voicechat. The far less serious tone of the name nicely reflects my current attitude towards games. Plus people often start humming or singing the songs just from seeing the name, and playing the actual song at that point never seems to fail to entertain lobbies. More than once I've turned left 4 dead games into impromptu danceparties this way. I'm not sure why, but everyone just seems to love scatman john

Occasional batman-scatman puns also never seem to get old. Quickly team, to the scatmobile!