To address the earlier argument of what would hurt more, this walnut or a paintball. I looked up pictures of the walnuts posted compared to other objects. The biggest I found was a bit smaller then a baseball. However, I've been hit by a baseball that was thrown and it honestly did not hurt much if at all. It left no bruising either. Now, on to a paintball. The average muzzle velocity of a paintball gun is 300 FPS or Feet Per Second. Converted that means the average paintball travels at roughly 204 MPH. No matter what, a paintball is going to pack a bigger punch then any sized walnut because it has velocity on its side. No matter how fast this kid threw he will never be able to even come close to the speed of a paintball.
In the contest of which would hurt worse, paintball or walnut. Paintball wins, no contest.