Some people masturbate by using machines that simulate intercourse. 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. Particular areas and processes of the body that change during pregnancy may also become the focus of psychological investment, but nudity or sexual activity is not always essential, and in some cases actual pregnancy is not necessary to invoke arousal. Women with women Main article: Lesbianism in erotica: Lesbianism in contemporary pornography Lesbian or girl-girl pornography features women engaged in sex together, but is typically aimed at a male audience. Boots are seen as the perhaps most fetishistic of all footwear and boots naked milf may be the most popular fetish clothing attire. Content featuring male bisexuality has been a growing trend since the advent of internet pornography. This makes varying degrees of stimulation an integral part of oral sex for many gay hentai men. Point of view pornography is adult entertainment filmed to look as if the watcher were experiencing the sex act themselves. 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. The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place. Some aspects of the research community distinguish between female ejaculation and what is colloquially known as squirting or gushing. Preggo pornography features pregnant performers and may include erotic lactation as a fetish. Such ejaculation can be done by mammary intercourse, or masturbation over the other person, or result from the withdrawal of the penis from a partner mouth as he is ejaculating following fellatio, irrumatio, or intercourse. Felching is a sexual practice involving the act of orally sucking semen out of the vagina or anus of one videos gays partner.