Soft swinging is when a couple engages in sexual activities with only each other while other couples perform sex acts in the immediate vicinity. The queening stool is also related to a smotherbox, which also allows the person under the seat to be locked in place, restrained by the neck as in a set of stocks. Reading or viewing pornography, sexual fantasy or other erotic stimuli may lead to a desire for sexual release such as by masturbation. Gonzo pornography is a style of pornographic film that attempts to place the viewer directly into the scene. A threesome is also depicted with one woman and two men who all perform sex acts on each other . When early sexologists in the late 19th century began to categorize and describe homosexual behavior, hampered by a lack of knowledge about homosexuality or women sexuality, they distinguished lesbians as women who did not adhere to female gender roles and incorrectly designated them mentally ill—a designation which has been reversed in the global scientific community. The term has also applied to other professions and even companies trying to appeal to a gay demographic. See horny milfs also Gay-for-pay. Bra pornography involves women or men dressed in bras. Some people masturbate by using machines that simulate intercourse. Lying face down one may use the hands, one may straddle a pillow, the corner or edge of the bed, a partner leg or some scrunched-up clothing and hump the vulva and clitoris against it. Penetration may involve use of fingers, toes, sex toys, or gay bear porn penises. In POV porn, the shooting style is generally similar to gonzo pornography, with the person receiving sexual gratification holding the camera him or herself—aiming it down at the actress or actor who is performing the sex act. Ass to mouth is a slang term primarily used to describe the withdrawal of a penis from the receptive partner anus followed by the immediate insertion into the receptive hentai movies partner mouth. It is typically animated pornography, as the legal age to be featured in a pornographic film in Japan is 18.