Yuri : Featuring two grown adult women in a homosexual/lesbian relationship. Being forced to wear diapers as a form of humiliation is sometimes a behavior encountered in sexual masochism. Behind the Green Door was one of the first pornographic films videos gays to feature sex between a white actress with a black actor . The term BDSM dates back to 1969; however, the origin of the term BDSM is unclear and is believed to have been formed either from joining the term B&D with S&M , or as a compound initialism from B&D, D&S , and S&M. 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. Some masturbate only using pressure applied to the clitoris without direct contact, for example by pressing the palm or ball of the hand against underwear or other clothing. In these research publications, it is suggested that real female ejaculation is the release of a very scanty, thick, and whitish fluid from the female prostate, while the squirting or gushing shown frequently in pornography is a different phenomenon, the expulsion of clear and abundant fluid, which has been shown to be a diluted fluid from the urinary bladder. In the 18th and 19th centuries, some European theologians and physicians described it as heinous, deplorable, and hideous, but during the 20th century, these taboos generally declined. Some 3d hentai pornographic films use an artificial semen substitute horny milfs to simulate or enhance creampie shots. A celebrity can fight the release in court to maintain deniability while still enjoying the career benefits. Real school shots or videos which are sexualized may violate privacy laws in some countries. Biological anthropologist Helen B. Hermaphrodite, also known as herm, refers to pornography, typically hentai, that features persons with the genitalia of both sexes. Macrophilia is a fascination with or a sexual fantasy involving giants, more commonly expressed as giantesses . His most famous model was Bettie Page, who became the first celebrity of bondage film and photography.