Pervert

A pervert (n) is a person with sexual preferences one may find unusual or disturbing. Usage: "That guy's a pervert, he enjoys anal sex/oral sex/masturbation/BDSM/insert your particular hang-up here."

To pervert (v) is to twist something, often beyond recognition. Usage: "Creationists will often pervert science to bolster their case".

An act performed by a pervert is called a "perversion", or alternatively, "fun".

Many sexual acts which were previously considered perversions have become increasingly perceived as "normal." The list includes homosexuality, masturbation, cunnilingus and fellatio (Bill Clinton popularized that one).