How'd you hurt your knee?

I wish I had a more exciting & sexy answer to this question but I was literally on the G train looking at the subway map... then all of a sudden I felt a sharp shooting pain in my right knee. So basically it hurts anytime I put any pressure on it - ie. standing or walking. Hmmm. This could be tricky. Alright, the jig is up - who has the voodoo doll?