Although pornography has usually focused on heterosexuality, due to the prevalence of the heterosexual orientation, explicit gay material has a long history as well, which reaches back to Greek antiquity, if not to prehistory. Technically this is a form of exhibitionism rather than group sex per se. When sexual activity is centered on one of the threesome, then the activity may be described as a gang bang of the person. Given the wide range of practices, some of which may be engaged in by people who do not consider themselves as practicing BDSM, inclusion in the BDSM community or subculture is usually dependent on self-identification and shared experience. Babysitter pornography features usually teenage girls being exploited and having taboo sex with older, male employers. As amateurs in a single segment of a multi-part video, the actresses are typically paid only about 50,000 yen . There is also some evidence that pornography can be used to treat voyeurism. The effect is to give the viewer the sense that they are experiencing the sex acts that they are watching, as opposed to simply watching others as a voyeur. A pearl necklace is a slang term referring to a sexual act in which a man ejaculates semen on or near the neck, chest, or breast of another person. Each participant may engage in any type of sex acts with one or both of the others, such porn milf as vaginal, anal or oral sex or mutual masturbation. Hentai is the various forms of Japanese pornography, including H-manga, H-anime, and H-computer games. Freud, however, considered such extensions of sexual interest to fall within the range of the normal, unless marked out by exclusivity . The name of the practice, when it is done in a repeated in-and-out motion, is derived gay boy porn from its passing resemblance to the dipping of a tea bag into a cup of hot water as a method of brewing tea. This category also includes pornographic home movies. Such films lesbian hentai continued to be produced but could only be distributed by underground channels.