An acronym for a medical condition known as "Red-Ass Dick Syndrome". Usually caused by excessive amounts of dry humping, resulting in severe chafing of the skin just below the head of the penis. Sufferers of RADS often experience pain while walking, running, having sex, jerking off, eating, driving, and breathing. The only known cure is to get with chicks who are easy so that you can actually have sex.
Check out Jesse over there. He's gotta walk half bent-over because he got a bad case of RADS Saturday night.