The scenario is a genre of erotica, which on the internet is sometimes abbreviated to CMNF, and may involve sexual and nonsexual erotic scenarios. These agreements are binding in the sense that the parties have the expectation that the negotiated rules will be followed. The porn industry and viewing public were shocked by the then-taboo spectacle of a white woman having sex with a black man. It is sometimes described as a sexual fantasy, by women or men, depicting an exhibitionist or physique worship scenario. The Silent Duck, also called Duck-Billing, is the technique hentai sex often used in which the person engaging in hand insertion shapes the hand to resemble a duck beak. In modern BDSM vernacular, the queening stool allows open access to the crotch while seated. For legal reasons, the vast majority of so-called reality porn involves professional actors and actresses posing as so-called amateurs. Bondage/BDSM Bondage pornography features performers tied up or constrained in various ways. The smotherbox is placed on a stable surface. These scenes may involve the female actor calling for the shot to be directed at some specific part of her body. Foot fetish pornography features heavy emphasis on the feet of the participants, either in combination with kissing and genital sex or in the context of acts such as trampling or crush fetishism. Mammary intercourse is said by Alex Comfort to produce mutual orgasm in women with sensitive breasts , and it was one of the nine substitute exercises for penetrative sexual activities, as detailed milf fuck in the Paradis Charnels of 1903. Omorashi: The act of holding hot gay sex one own urine until the need to urinate is urgent, making another hold in their urine, or watching another person with an urgent need to urinate. Each participant may engage in any type of sex acts with one or both of the others, such as vaginal, anal or oral sex or mutual masturbation. The definition clash also appears with the English definition of yuri as any lesbian relationship, as opposed to its sexually explicit definition in Japan.