When he is in position the cover is closed. The person receiving anilingus is regarded as the passive partner in the act, and the person performing anilingus is the active partner. Using the term shemale for a transsexual woman often implies that she is working in the sex trade. Going back at least as far as the Christy twins in the 1970s, depictions of incest and particularly incest between twins has been a feature of gay pornography. In some societies, the terms fox, plum, chick, or chicken are preferred. Sexologist Alfred Kind suggested that the buttocks is the primary sexual presentation site in primates. Others may also use vibrators and other sexual devices more hentai porn commonly associated with female masturbation. The first pegging scene appears to have been in the non-pornographic 1970 film Myra Breckinridge, based on the novel of the same name by Gore Vidal, although it was not explicit. A somewhat controversial ejaculation control technique is to put pressure on the perineum, about halfway between the scrotum and the anus, just before ejaculating. Voyeurism: Seeing another urinate without the celebrity porn person knowledge either through video taping by a hidden camera, or by lurking in locations where people are urinating or are likely to have an urge to urinate. Enema pornography involves adults given momsex enemas gay boy porn to others, often fake. The padding may also muffle gay bear porn noises from the outside, causing a relaxation effect and heightening their other senses. Unlike erotic films, pornographic films contain explicit sexuality and do not claim any artistic merit. Gloryhole pornography features women performing fellatio on unidentified men through a small hole made in a bathroom divider. The rise of the Internet in the late 1990s and early 2000s similarly changed the way pornography film was distributed and furthermore complicated the censorship regimes around the world and the legal prosecution of obscenity. Internal ejaculations, followed by images of semen dripping from the anus, are sometimes depicted in bareback gay pornography, where they are referred to by the term breeding or the reverse money shot.