In "The Return of the Fellowship of the Ring to the Two Towers" Randy accidentally gets it mixed up with the Lord of the Rings, and the boys give it to Butters.
It is apparently bad enough to drive Butters to act like Gollum, and to turn Token catatonic. It is known that it includes multiple penetration, urine, thousand island dressing, sixty-nining, spanking, midgets, and vaginal penetration with telephones, staplers, and magazines. Other than that, the content is unknown, which is probably for the best.
According to the DVD commentary, the audio track heard during the episode is from an actual porn film.