Lesbianism has been a theme in erotic art since at least the time of ancient Rome, and many regard depictions of lesbianism to be erotic. The 1979 U. Anal sex or anal intercourse is generally the insertion and thrusting of the erect penis into a person anus, or anus and rectum, for sexual pleasure. BDSM is a variety of erotic practices involving dominance and submission, role-playing, restraint, and other interpersonal dynamics. It may involve sexual attraction to women who are pregnant or appear pregnant, attraction to lactation, or attraction to particular stages of pregnancy such as impregnation or childbirth. Snuff pornography involves the actual death of any of the participants, consenting or otherwise, simulated death is not considered snuff. Tentacle rape or shokushu goukan is found in some horror or hentai titles, with tentacled creatures having sexual intercourse with female characters. Strictly speaking, bondage gay bear porn means binding the partner by tying their appendages together; for example, hentai movies by the lesbian milfs use of handcuffs or by lashing their arms to an object. Pornographic films present sexual fantasies and usually include erotically stimulating material such as nudity. Cum-shot pornography features a collection of male ejaculation scenes. Generally, interest differs between people, and gender depends on sexual orientation. The buttocks in human females thus contain more adipose tissue than in males, especially after puberty. Spanking or whipping pornography involves spanking or whipping, generally of the buttocks, with the hand or with other objects such as belts, switches, paddles, brushes, or whips. Twink pornography features younger performers, and usually features young men under 30 who identify as gay or bisexual. A facial is a form of non-penetrative sex, though it is generally performed after some other means of sexual stimulation, such as vaginal sex, anal sex, oral sex or masturbation. Consent is the most important criterion here. An orgy is a gathering where guests freely engage in open and unrestrained sexual activity or group sex; and a bunga bunga orgy is an orgy in which participants have sex underwater, such as in a swimming pool or a hot tub.