I haven't, but my brother has a great story.
Our high school baseball team goes to Florida every spring break in March for some informal practice and scrimmages. Technically, it's supposed to be run by parents, but the coaches still have some involvement anyway. During the first few days down there, we do some station to station work with hitting, bunting, and fielding. The bunting station was notoriously famous because the pitching machine used to deliver the balls was cranked all way to 90 mph and positioned fifteen feet in front of the mound in order to increase the difficulty. We were told to square around, and place the ball down the third baseline. When my brother's turn came up (he was only a sophomore), he had trouble making contact for the first few pitches. He hung in there, but on the last pitch, the ball that was put into the machine had a small cut in it. When it went through the machine, the ball started curving almost immediately. At that speed and distance, he didn't even have time to react. The ball hit him square in the testicles. The force of the shot (and probably the pain) knocked him unconscious.
For some idiotic reason, he wasn't wearing a cup that day, and was taken to the emergency room right away. His testicles swelled up like grapefruits and he missed the rest of the week's practice while recovering. He didn't suffer any long term damage, but he was in pain for awhile. He also definitely started wearing a cup after that whenever he was on the field. Today, he has two kids, so apparently it wasn't as bad as it could have been.