Depictions of male and female masturbation are common in pornography, including gay pornography. The concept of lesbian, to differentiate women with a shared sexual orientation, is a 20th-century construct. Hentai is the various forms of Japanese pornography, including H-manga, H-anime, and H-computer games. Sexologist Alfred Kind suggested that the buttocks is the primary sexual presentation site in primates. It is sometimes combined with BDSM features. The term combines elements of the Freudian psychoanalytic fetish and the Marxist commodity fetish, and is used in the context of British, Spanish and hentai sex French colonialism and imperialism and their aftereffects. These agreements are binding in the sense that the parties have the expectation that the negotiated rules will be followed. As of 2013, little analysis of this paraphilia has been reported in medical literature. Lesbian pornography made for women is usually made by women, and usually features women who identify as lesbian or bisexual. This industry employs thousands of performers along with support and production staff. Babysitter pornography features usually teenage girls being exploited and having taboo sex with older, male employers. They further argue that setting a discrete line between safe and not-safe activities ideologically denies consenting adults the right to evaluate risks vs rewards for themselves; that some adults will be drawn to certain activities regardless of the milf fuck risk; and that BDSM play—particularly higher-risk play or edgeplay—should be treated with the same regard as extreme sports, with both respect and the demand that practitioners educate themselves and practice the higher-risk activities to decrease risk. Women porn is often produced by women and aimed specifically at the female market - rejecting the view that men are turned on by porn but women only by a box of chocolates. Facial cum shots are currently regularly videos gays portrayed in pornographic films and videos, often as a way to close a scene.