In human sexuality, a threesome is sexual activity that involves three people at the same time. Bukkake pornography involves a performer, usually female, onto whom several men or women ejaculate, usually on the face. Is also common of the furry genre. There has been an increase in discussion and portrayal of masturbation in art, popular music, television, films, and literature. The concept of lesbian, to differentiate women with a shared sexual orientation, is a 20th-century construct. Diaper pornography involves performers wearing diapers, sometimes with an adult performer acting in the role of a caretaker. What seems clear from the historical record is that much of the lesbian material in pornographic texts was intended for a male readership. A few extremely flexible males can reach and stimulate their penis with their tongue or lips, and so perform autofellatio. Normal quantities of ejaculate hentai videos range from 1.5 to 5.0 milliliters . Use of the agreed safeword is seen by some as an explicit withdrawal of consent. Older names for a pornographic film include young gay porn stag film, and blue movie. Although interracial pornography theoretically can apply to depictions of sexual activity between performers of any different racial groups, the term is most commonly used for heterosexual sex acts between black and white performers. 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. The use of the word creampie naked milf to describe such scenes originated in U. It is also followed by dedicated industry publications and trade groups as well as the mainstream press, private organizations , government agencies, and political organizations. The Silent Duck, also called Duck-Billing, is the technique often used in which the person engaging in hand insertion shapes the hand to resemble a duck beak. Cuckolding can also be mixed with other non-monogamous relationship arrangements with which it has substantial overlap such as Swinging, wife-swapping, open relationships, and polyamory, etc.