Patricia Hill Collins, an African-American writer, theorizes that this is derived from a stereotype that those of black descent are promiscuous, and their buttocks are objectified by porn as a result. Multiple men and women Bisexual pornography features one woman and two men who all perform sex acts on each other. Is also common of hentai movies the furry genre. This is commonly called double vaginal penetration or double stuffing. Internationally, hentai is a catch-all term to describe a genre of anime and manga pornography. Cum shots typically do not appear in girl-girl scenes and orgasm is normally implied by utterances, gay boy porn cinematic conventions, or body movement. 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. Mutual masturbation, mutual manual stimulation of the genitals between partners, can be a substitute for sexual penetration. Mammary intercourse is a sex act, performed as foreplay or as non-penetrative sex, that involves the stimulation of the male penis by the female breasts and vice versa. In Japanese, this natural-fibre rope is known as asanawa; the Japanese vocabulary does not make a distinction between hemp and jute. Rainbow parties were covered on The Oprah Winfrey Show in 2003, and became the subject of a juvenile novel called Rainbow Party. The name was coined from the title of the controversial book. Lying face down on a comfortable surface such as a mattress or pillow, the penis can be rubbed against it. For circumcised males, on whom the glans is mostly or completely uncovered, this technique creates more direct contact between the hand and the glans. Its primary goal is sexual arousal in its audience. The volume of semen that is ejaculated depends on several factors, including the male health, age, degree of sexual excitement, and the time since his last ejaculation. This type of pornography is almost exclusively hentai, as true hermaphroditic momsex humans are not fertile and are not usually found in nature.