An old roommate contracted this. It was an after-effect of a case of gonorrhea. His testicle swelled up until it looked like a banana. He was in so much pain he could hardly walk.
I found it difficult to be too sympathetic. The gonorrhea showed up after he bragged about fucking three different girls in three days (all unprotected, of course) - and then bragged more because the nurse who injected him with penicillin was hitting on him. If he'd been home sucking my dick like he should have been, it never would have happened.