Post Masturbation Syndrome. This form of PMS is experienced by some men after they had been masturbating for a prolonged amount of time (typically 30-35 minutes). The primary symptom is a weak arm in combonation with fatigue, making it difficult to do things such as write, type, draw or use your computers mouse.
Zach: "Dude, last night I was jerkin' it right, and it took me like half an hour to finish. After, my arm felt like it was dead!"
Mike: "Dude, sounds like you got yourself a case of Male PMS".