In a recent interview, Jimmy Kimmel revealed that he had to have several surgeries on the most delicate part of his body. Apparently, his urethra had closed up, and it took more than one try to get it to open back up. (In all honesty, I'd rather not go into any detail because just talking about this sort of stuff makes me physically uncomfortable.)
Famous people have health issues, just like us. Usually, they love to talk about them after the fact, because it makes them look sympathetic. Unfortunately for Jimmy Kimmel, he had his health emergency on a part of the body that makes everybody giggle. I'd say he's brave for talking about something so personal and embarrassing, but I'm pretty sure he did it because it's the sort of thing he likes to joke about. This would be like if Carrot Top got a prop stuck up his butt. For anyone else, that'd be super embarrassing. For him, it just becomes part of the act.
Kimmel isn't the first celebrity to have issues with his biscuit. Here's a collection of other celebs who have had problems with their "members."