"The 120 Days of Sodom" is arguably the most perverted text ever put to paper. and a literature "classic".
This novel by Marquis de Sade relates the story of four wealthy men who enslave 24 mostly teenaged victims and sexually torture them while listening to stories told by old prostitutes. The book was written while Sade was imprisoned in the Bastille and the manuscript was lost during the storming of the Bastille. Sade wrote that he "wept tears of blood" over the manuscript's loss. Many consider this to be Sade crowning achievement.