Arguably the most famous example of the genre is the Taboo series. 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. Can also include mature milfs auto-fellatio, anime hentai or performing oral sex on oneself. Ethnic pornography is a genre of pornography that features performers of specific ethnic groups, or depictions of interracial sexual activity. Crying pornography that features participating actors crying. BDSM pornography depicts bondage and discipline, domination and submission, sadism and masochism. The nipples are erogenous zones, and vigorous stimulation of them during masturbation usually causes the penis to become erect more quickly than it would otherwise. For other scenes, particularly in established relationships, a safeword may be agreed to signify a warning rather than explicit withdrawal of consent; and a few choose not to gay sex video use a safeword at all. An orgy is a gathering where guests freely engage in open and unrestrained sexual activity or group sex; and a bunga bunga orgy is an orgy in which participants have sex underwater, such as in a swimming pool or a hot tub. Foot fetishism, foot partialism, foot worship, or podophilia is a pronounced sexual interest in feet. Amateur porn has been called one of the most profitable and long-lasting genres of pornography. Bondage is usually, but not always, a sexual practice. Partners can engage in penetrative sex, known as full swap, or choose to soft swap in which they engage only in non-penetrative sex. As with most forms of sexual activity, anal sex participants risk contracting sexually transmitted infections . Pornographic films are generally classified into sub-genres which describe the sexual fantasy which the film and actors attempt to create. Big Beautiful Woman is a euphemism for an overweight woman and is frequently used in the context of fat fetishism. Men and women may masturbate until they are close to orgasm, stop for a while to reduce excitement, and then resume masturbating.