Jimp, or J.I.M.P means Jizzed In My Pants. Occurs most with people who have premature ejaculations, or people in prison who haven't had sex for quite a long time after they were caught "interfering" with children.
1. Wow, this bikini car-wash is hot. Oops, I seem to have Jimped...
2. Ooo, a light breeze is coming under my cell door.... ah crap, not again...