I got hit in the head the other day while paintballing and it was one of the most painful things I can remember.
I only remember 2 other very painful events
1) My yard is outlined by a stone wall, and I had hopped over the wall for some reason or another. The ground is a little bit lower on the other side of the wall, and so I needed a piece of wood to lean against the wall to stand on and give me a boost to be able to climb over. It was evening, and there was only a little bit of light left. I saw a piece of 2x4 laying on the ground nearby, so i propped it up and hopped on. I instantly felt an EXCRUCIATING pain in the soft part of my foot. I stepped down and lifted my foot, and the board was stuck to my foot. A nail had gone through my shoe and pierced a little into my foot. Hurt like a mad.
2) Another painful experience was hopping from rock to rock in a lake nearby. I slipped and my foot fell between the crack of the rocks and I banged my need down on a point on the stone with all my weight. That was the most painful experience I can remember. I nearly passed out, I could not take it.
I was paintballing yesterday, and I got hit roughly 5 times on the top of my head (which is not protected by the mask). It seriously felt like someone was throwing rocks at my head. It knocked me backwards and gave me a serious migrane.
http://www.blike.com/paintballing/DSC00054.jpg