I hit myself in the nuts one time. It must have been 25 years ago. We were all standing around the table trying to get 9 rails on a GC. Somehow when I took my attempts, the CB got slightly airborne on the second rail, then higher off the third rail, then right into my junk. It hurt too. ha ha.
Another time in a room with tables lined end to end, the opponent on my table was breaking, while the next table the guy was racking. My breaker scooped the CB right into the back of the neck on the next table. We were all bangers then. I learned real quick from that point on how and when to stand when someone is breaking. The guy that got hit was ok.
I've also seen in banger days the guy would rack, and the opponent would break real fast as the racker was putting the rack away. No thanks. I learned from that to keep the CB until the racker is well out of the way. Not an issue with experienced players, only bangers do this, in my experience.