Amateur porn has been called one of the most profitable and long-lasting genres of pornography. The Japanese lesbian hentai sex industry uses the term Paizuri . The term lesbian is also used with regard to sexual identity or sexual behavior, regardless of sexual orientation, or as an adjective to characterize or associate nouns with female homosexuality or same-sex attraction. This is commonly called double anal or nude milfs double stuffing. In addition to mainstream pornography, the popularity of facials has led to creation of its own niche market, like video series that specialize in showing the act. BDSM is a variety of erotic practices involving dominance and submission, role-playing, restraint, and other interpersonal dynamics. Said that the female buttocks evolved in the context of females competing for the attention and parental commitment of powerful resource-controlling males as an honest display of fat reserves that could not be confused with another type of tissue, although T. This may relate to fetishes such as voyeurism or cuckolding. Insertion in pornography features women inserting various odd objects into their anus or vaginas. The buttocks in human females thus contain more adipose tissue than in males, especially after puberty. Related genres include: Amateur pornography originally referred only to pornography produced by amateurs but now also includes professionally made pornography designed to appear as if it were amateur. Softcore pornography generally contains nudity or partial nudity in sexually suggestive situations, but without explicit sexual activity, sexual penetration or extreme fetishism, while hardcore pornography may contain graphic sexual activity and visible penetration, including unsimulated sex scenes. Since at least 1973, it has also been used to refer to a sexually attractive young woman. The nipples are erogenous zones, and vigorous stimulation hot gay sex of them during masturbation usually causes the penis to become erect more quickly than it would otherwise. Pornographic films present sexual fantasies and usually include erotically stimulating material such as nudity.