How about these:
Sifu Keith
Sensei Keith
K
Well, not very catchy. But I tried!
Try the baby section. They always have questions about names on there and the answerers there are much more experience with picking names.
Keith the Killer -insert last name here-...
Keith KAPOW!
Anyway those are my two *bad nicknames. If you want a fighting nickname as your sparring partners to give you one based on what they think. It's always better getting a nickname given to you than to give yourself one.
I have to comment on your remarkable ability to choose categories for questions????