A sex party is a gathering at which sexual activity takes place. Since mammary intercourse is a non-penetrative sex act, the risk of passing a sexually transmitted infection that requires direct contact between the mucous membranes and pre-ejaculate or semen is greatly reduced. On the other hand, the masochist enjoys being hurt, humiliated, or suffering within the consensual scenario. Pornography may be presented in a variety of media, including books, magazines, postcards, photographs, sculpture, drawing, painting, animation, sound recording, film, video, and video games. For example, in Australia it is rated Refused Classification . Several hundred exclusively pegging films were produced, as well as twice as many bisexual and straight films with strap-on scenes. This mature milfs can, however, redirect semen into the bladder . The reverse of this, in which nude women interact with clothed men, is called Clothed male, naked female . John Stagliano is considered to have started the gonzo pornography genre with his Buttman series of films. Group sex most commonly takes place in a private sex party or semi-public swinger gathering, but may also take place at massage parlors or brothels or, in some jurisdictions, at purpose-built locations such as sex clubs. It has also been recommended as a form of foreplay or safer sex. It is also followed by dedicated industry publications and trade groups as well gay hentai as the mainstream press, private organizations , government agencies, and political organizations. Multiple men and women Bisexual pornography features one woman and two men who all perform sex acts on each other. Jerk off instruction features a performer encouraging or instructing the viewer to masturbate, gay boy porn often culminating in a countdown at the end of which the viewer is invited to induce orgasm. 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.