The interaction between tops and bottoms—where physical or mental control of the bottom is surrendered to the top—is sometimes known as power exchange, whether in the context of an encounter or a relationship. It has been described as professionally gay sex video made porn which seeks to emulate the style of amateur pornography. In anime hentai a separate article analyzing 12 men who engaged in bestiality, an additional analysis of an 11-man subgroup revealed that 6 had engaged in coprophilic behavior, compared with only 1 in the matched control group consisting of 12 SM-oriented males who did not engage in bestiality. Common phrases used to refer to these individuals are chicks with dicks, trannies, or shemales, although these are generally considered pejorative slurs among transwomen. Fisting involves the insertion of one partner entire hand into a vagina or the anal cavity. The surfacing of sex tapes has become so common that some are leaked as a marketing tool to advance or establish a media career. The principal characteristic of voyeurism is that the voyeur does not normally interact directly with the subject of his/her interest, who is often unaware of being observed. While most tentacle erotica is animated, there are also a few live-action movies. Erotic literature and pornographic films have been devoted to the sexual uses of glory holes. Enema pornography involves adults given enemas to others, often fake. Crying pornography that features participating actors crying. The anal and rectal tissues are delicate and do not provide natural lubrication, so they can easily tear and permit disease transmission, especially if lubricant is not used. Through the 1990s, mainstream movie and television actors have been more willing to portray homosexuality, as the threat of any backlash against their careers has lessened and society acceptance of gay and lesbian people has increased. Sexual scenarios may involve male domination, female submission, exhibitionism and erotic milf fuck entertainment. The most established and probably most cliché set form of dominance and submission is Dominance and slavery.