In the s, it was assumed that unprotected fisting—which often produces small injuries to the anus, permitting microorganisms access to the blood—was an easy route for transmission of HIV. This, combined with sexual squeamishness towards the public fisting culture in gay establishments of San Francisco, led gay writer Randy Shilts to successfully campaign for the closure of venues, such as gay bathhouses and sex clubs, that openly permitted it. Typically, fisting does not involve forcing the clenched fist into the vagina or rectum; this is a practice called "punching". Instead, all five fingers are kept straight and held as close together as possible forming the beak -like "duck" , then slowly inserted into a well lubricated vagina or rectum. Fistees who are more experienced may take two fists double-fisting. In the case of double-fisting, pleasure is derived more from the stretching of the anus or vagina than from the thrusting in-and-out movement of hands.