I actually thought Neer had that nickname because he's all snaggle-toothed and stuff. I heard Lister got that nickname because people were always ducking him, scared of him or something. That makes sense.
My favorite nicknames are the ones that aren't self-styled, meaning the fighter didn't just call himself that for whatever reason. Jeremy "Gumby" Horn, Frank "Twinkletoes" Trigg, and Mike "Quick" Swick come to mind. Hell, I remember when Rogan started calling him Quick.