Did not happen to me but back in 9th grade ( 1981 ??) my school had one of those leg press machine where you lay on your back. The weights are loaded from the top so that the plates slide straight down a pole. This was for standard plates, not Olympic.
One of my friends was loading the machine with 75 lbs York plates. he ended up getting his crotch area too close to the machine. He ended up getting the tip of his penis caught between two 75 lb plates. Must have been those skimpy Bill Clinton type running shorts that did not offer that much protection.
He retreats to a corner and we ask him what was wrong. He turns around and pulls down his short to expose a giant blood blister on his penis. There were five of us in the weight room and everyone who was holding a barbell or dumbell dropped them to the floor. Considering he was 15 years old he was terrified that his member would be permantley injured.
He went to the doctor's office but left with no treatment after a female nurse first asked him what was wrong. Needless to say, he was much carefull about the leg press machine.