After the prerequisite level of sexual stimulation has been achieved, and ejaculation becomes imminent, the male will position his penis so that the semen discharged will be deposited onto his partner face. Going back at least as far as the Christy twins in the 1970s, depictions of incest and particularly horny milfs incest between twins has been a feature of gay pornography. Consent is the most important criterion here. A female dominant in a master/slave relationship is often termed a Mistress, not to be confused with the colloquial usage of mistress as a kept sexual partner without a similarly formalized power relationship. Some couples use pornography at times for variety and to create a sexual interest or as part of foreplay. Sloppy seconds is a slang phrase for when a man has sexual intercourse with another person who already has received another man penis in the relevant orifice and is therefore wet or sloppy. In the 1970s, the hardcore pornography genre introduced the stereotypical cumshot scene as a central element of the hardcore film, in which the male actor ejaculates in a way ensuring maximum visibility of the act itself. Lesbian pornography made for women is usually made by women, and usually features women who identify as lesbian or bisexual. Simultaneous penetration of the mouth and either the vagina or anus. Unlike Yaoi, Bara is normally made by actual homosexual men, for homosexual men, and tends to focus on the more realistic obstacles and challenges that come with being homosexual in Japan. It may be used as foreplay, or as an alternative to sexual penetration. The most common depiction of a hermaphrodite is a person with a female face, breasts, and build, and a penis , although there are other combinations. Clothed female, naked male is a genre of erotica featuring one or more nude men lesbian hentai and one or more clothed women. Guro or Gore is a genre of Japanese pornography involving blood, gore, disfiguration, violence, mutilation, urine, enemas, or feces. The interaction between tops and bottoms—where gay sex video physical or mental control of the bottom is surrendered to the top—is sometimes known as power exchange, whether in the context of an encounter or a relationship.