This disease is named after South Park character Kenny McCormick. Kenny suffered from this disease during the second episode of the third season of the show. The disease affects men of all ages, but especially those who are in the first stages of a relationship. The disease is caused by holding in flatulence. In a minor case of this disease, the victim may experience mild stomach pain and have powerful flatulence for hours after his girlfriend leaves. In an advanced case, such as Kenny's, it could lead to death by spontaneous combustion.
Guy (having just departed from his bedroom after spending the night with his new girlfriend) to his male friend: "Dude, I've got Kenny disease real bad."
(Followed by serious flatulence.)