Well, it's kind of a funny story. I became the KneeCaptain during my character creation in a game called Dragon's Dogma, or Dergon's Dergma depending on who you ask. It was here that I decided to make a muscled dwarf-like character with flowing ginger locks and a flowing ginger beard. He was going to be called KneeCapin'Sam as a joke on his stature and because it's fun to imagine a ginger dwarf taking out armies of dudes at the knees. Sadly, the character name slot was not long enough for the name and KneeCaptain became my moniker for Dragon's Dogma. Since then I've kept using it because it helps me to remember to not take myself to seriously.