Solo performances in gay pornography have been described in 1985 as either or both active and/or passive , whereas female solo performances are said to be exclusively passive . A scene where many women have sex with one man is referred to as a reverse gang-bang. The industry generally refers to such films as adult films, which is part of adult entertainment. Although there may be no connection between coprophilia and sadomasochism , the limited data on the former comes from studies of the latter. Since mammary intercourse is a non-penetrative sex act, the risk of passing a sexually transmitted infection that requires direct contact between the mucous membranes and pre-ejaculate or semen is greatly reduced. The name was coined from the title of the controversial naked milf book. The term sadomasochism is derived from the words sadism and masochism . Irrespective of the legal or social view of pornography, it has been used in a number of contexts. Some are aroused from wetting their diapers, others like messing their diapers. Contrary to the other two types, B/D does not define the Tops and Bottoms itself, and is used to describe the general activities with either partner being the receiver and the giver. The existence of such content gay cock in commercially available pornography is widely considered an urban legend. This type of pornography is almost exclusively hentai, as true hermaphroditic humans are not fertile and are not usually found in nature. Breast fetishism is a paraphilic sexual interest focused on female breasts . A bisexual threesome may involve a man having sex with a man and a woman, the woman having sex with a man and a woman, or all three having sex with each other. Interactive pornography, available in CD-ROM and DVD format, allows the viewer to select the particular acts performed at any one time, sometimes with the camera providing a first person view. Lesbian hentai movies pornography typically features a wider range of appearances and body types than is typical of mainstream pornography.