Sexual orientation Pornography features an increasing variety of combinations of actors by their sexual orientation such as lesbian, gay, bisexual, and transsexuals in addition to traditional heterosexual roles. Originating in Japan in the 1980s, the genre subsequently spread to North America and Europe, and crossed over into gay pornography. Transsexual pornography is a genre of pornography. In S/M, the Sadist is usually the Top and the Masochist the Bottom, but these roles are frequently more complicated or jumbled . Since the 1980s, many practitioners and organizations have adopted the motto safe, sane and consensual, commonly abbreviated as SSC, which means that everything is based on safe activities, that all participants be of sufficiently sound/sane mind to consent, and that all participants lesbian milfs do consent. Softcore gay pornography also exists; it at one time constituted the genre, and may be produced as beefcake pornography for heterosexual female and homosexual male consumption. Lying face down on a comfortable surface such as a mattress or pillow, the penis can be rubbed against it. Femdom features BDSM scenes gay twink porn in which the dominant partner is female. Animal masturbation has been observed in many species, both in the wild and in captivity. Threesome can also refer to a love triangle, a three-way romantic relationship. The most common type of erotic spanking is administered on the bare buttocks, but can also hentai movies be combined with bondage, in order to heighten sexual arousal and feelings of helplessness. Female dominance refers to BDSM relationships and BDSM scenes in which the dominant partner is female. Rape pornography features performers simulating rape. Entacle erotica describes a type of pornography most commonly found in Japan which integrates traditional pornography with elements of bestiality and a fantasy, horror, or science-fiction theme. Starting with erotic stories and woodblock prints from before the 20th century, Japanese pornography evolved into distinct subcategories with the media that in addition of pornographic videos and magazines featuring live actors, there is exist categories of pornographic manga , pornographic computer games , and pornographic anime .