Female masturbation involves the stroking or rubbing of a woman vulva, especially her clitoris, with an index or middle fingers, or both. Following World War II, during a period of social repression when governments actively persecuted homosexuals, women developed networks to socialize with and educate each other. Typically features adult, masculine men with varying degrees of muscle, body fat, and body hair, akin to beefcakes, or bears. Preggo pornography features pregnant performers gay cock and may include erotic lactation as a fetish. Sadomasochism refers to the aspects of BDSM surrounding the exchange of physical or emotional pain. Sadism describes sexual pleasure derived by inflicting pain, degradation, humiliation on another person or causing another person to suffer. A scene where many women have sex with one man is referred to as a reverse gang-bang. When used as an alternative to penile-vaginal penetration, the goal may be to preserve virginity or to prevent pregnancy. In Japan, point of view pornography is referred to as hamedori . Exhibitionism: Becoming noticeably desperate or wetting oneself with the express purpose of being seen by strangers. 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 partner mouth. Felching is a sexual practice involving the act of orally sucking semen out of the vagina or anus of one partner. The use of the word creampie to describe such scenes originated naked milf in U. Contrary to the other two types, B/D does not define the Tops and Bottoms itself, and is used to describe the general activities with either partner being the receiver and the giver. Buttocks are sometimes emphasized in pornography, where they are often referred to as booty. Pantyhose/Tights/Stockings 3d hentai pornography involves women or men dressed in pantyhose, tights, or stockings. Some masturbate only using pressure applied to the clitoris without direct contact, for example by pressing the palm or ball of the hand against underwear or other clothing.