S&M
From wipipedia.org
S&M is an abbreviation of sadomasochism and forms a central theme in much of the sexuality associated with the fetish scene. Sadism is the sexual pleasure or gratification in the infliction of pain and suffering upon another person. Masochism, the sexual pleasure or gratification of having pain or suffering inflicted upon the self. For a more detailed explanation of S&M see sadomasochism.