Pervert's Cramp
A cramp in the hand one gets after continuous periods of masturbation. It normally occurs around the middle finger, ring finger, and pinky. Similar to a writer's cramp, but, well, it's for perverts.
Person #1: I was jacking off to a porno on the internet a few days ago, and I got this pain in my hand!
Person#2: Oh, that must've been a pervert's cramp.
Person#2: Oh, that must've been a pervert's cramp.