Two answers.
One: Not too long ago, I was in a bike wreck, and ended up with a cuncussion. The pain was mild, but the worst was the disorientation. I remember vividly the feeling of spiraling confusion. The world seemed to be constantly spinning even though I was looking straight. On a funny side note though, after a few days in the hospital, I went back to school to find many of the kids thought I was in a coma.
Two: It happened a while ago, and I may seem like a wuss but; I had to get all four of my baby canine teeth removed by surgery. The painkillers may work, but having eight shots on either side of the gums hurts like hell.