Biological anthropologist Helen B. Female masturbation involves the stroking or rubbing of a woman vulva, especially her clitoris, with an index or middle fingers, or both. 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. The term breast fetishism is also used to refer to cultural attention to female breasts and the sexuality they represent, with debate continuing as to whether the modern widespread fascination with breasts among heterosexual males in western societies is a sexual fetish. Unlike the usual power neutral relationships and play styles commonly followed by couples, activities and relationships within a BDSM context are often characterized by the participants taking on complementary, but unequal roles; thus, the idea of informed consent of both the partners becomes essential. Hermaphrodite, also known as herm, refers to pornography, typically hentai, that features persons with the genitalia of both sexes. It may occur more frequently in private situations, such as spontaneous sexual activity among three friends, or arranged in a community of like-minded swingers or planned as a once-only experience; and rarely in anonymous settings, such as at orgies or other sex parties. Snowballing or snowdropping is the human sexual practice in which one person takes someone else semen into his or her mouth and then passes it to the mouth of the other, usually through kissing. As women, they face concerns separate from men. Preggo pornography features pregnant performers hentai porn and may include erotic lactation as a fetish. Milking pornography features lactating women naked milf being milked or milking themselves . The term bondage describes the practice gay bear porn of Physical restraining. Whether or not licking and fondling is considered tea bagging was once debated on the Howard Stern Show. The primary subjects of pornographic depictions are pornographic models, who pose for still photographs, and pornographic actors or porn stars, who perform in pornographic films.