Frotteurism is a paraphilic interest in rubbing, usually one’s pelvis or erect penis, against a non-consenting person for sexual gratification. It may involve touching any part of the body including the genital area. A person who practices frotteurism is known as a frotteur. The majority of frotteurs are male and the majority of victims are female, although female on male, female on female, and male on male frotteurs exist. This activity is often done in circumstances where the victim cannot easily respond, in a public place such as a crowded train or concert.
Usually, such nonconsensual sexual contact is viewed as a criminal offense: a form of sexual assault albeit often classified as a misdemeanor with minor legal penalties. Conviction may result in a sentence or psychiatric treatment.