Diaper pornography involves performers wearing diapers, sometimes with an adult performer acting in the role of a caretaker. For circumcised males, on whom the glans is mostly or completely uncovered, this technique creates more direct contact between the hand and the glans. The concept of lesbian, to differentiate women with a shared sexual orientation, is a 20th-century construct. It is typically animated pornography, as the legal age to be featured in a pornographic film in Japan is 18. The smotherbox is placed on a stable surface. For example, in Australia it is rated Refused Classification . Softcore gay pornography also exists; it at one time constituted the genre, milf fuck and may be produced as beefcake pornography for heterosexual female and homosexual male consumption. Femdom features BDSM scenes in which the dominant partner is female. The most common type of erotic spanking is administered on the bare buttocks, but can also be combined with bondage, in order to heighten sexual arousal and feelings of helplessness. Examples include the Girls Gone Wild and Girls Who Like Girls Series. For instance, Amateur Allure has a trademark shot where the sexually performing cameraman circles a handycam around the sexually performing model head. In modern BDSM vernacular, the queening stool allows open access to the crotch while seated. English adopts and uses hentai as a genre of pornography by the commercial sale and marketing of explicit works under this label. Some techniques which may work for one individual can be difficult or uncomfortable for another. The full-weight body-pressure, gay hentai moisture, sex odors and darkness can be perceived as powerful sexual attractions or compulsions. The range of its individual characteristics is thereby wide. The phrase is commonly found on porn sites. Transgender pornography features performers who cross-dress for sexual gratification, either for themselves or for their partners. Sexologist Alfred Kind suggested gay sex video that the buttocks is the primary sexual presentation site in primates.