Fisting—also known as fist fucking (FF), handballing, and brachioproctic or brachiovaginal insertion—is a sexual activity that involves inserting one or more hands into the rectum or the vagina. Fisting may be performed on oneself (self-fisting) or performed on one person by another. People who engage in fisting are often called "fisters".

The Catacombs was a gay and lesbian S/M leather fisting club in the South of Market area of San Francisco, which operated from 1975 to 1981, and reopened at another location from 1982 to 1984. It was the most famous fisting club in the world. The founder and owner was Steve McEachern. The location was semi-secret and admission was by referral only. It was originally a gay men's club, but Cynthia Slater persuaded the management to open up to lesbians. Among the patrons was Patrick Califia, known then as Pat Califia. The Catacombs has been exhaustively described by sexual anthropologist Gayle Rubin, who calls it "exemplary" in its attempts to deal with the AIDS crisis which would eventually lead to its closure. Patrick Moore devotes a chapter to it in his Beyond Shame: Reclaiming the Abandoned History of Radical Gay Sexuality. Sex educator Carol Queen called it "the place to be seen and to play at during the 1980s."