Enema pornography involves adults given enemas to others, often fake. Human urinal: An act common in the bondage sex community where a male or female slave will serve as a urinal for a dominant partner. Given the wide range of practices, some of which may be engaged in by people who do not consider themselves as practicing BDSM, inclusion in the BDSM community or subculture is usually dependent on self-identification and shared experience. Big Beautiful Woman is a euphemism for an overweight woman and is frequently used in the context of fat fetishism. Yuri is the lesbian equivalent. Some productions are noted for sophisticated and/or experimental storytelling and animation techniques. 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. Technically this is a form of exhibitionism rather than group sex per se. In September 2003 the BBC reported on the new dogging craze. They are most often featured with male partners, but are also featured with other transsexuals or cissexual women. 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 gay porn in the context of an encounter or a relationship. Often, slave contracts are set out in writing to record the formal consent of the parties to the power exchange, stating their common vision of the relationship dynamic. Crying pornography that features participating actors crying. They may repeat this cycle multiple times. For other diaper fetishists, simply wearing a diaper, the bulking feeling and crinkling sounds associated with it, is enough to cause the fetishist a form of erotic pleasure or sexual arousal. Pornographic films are generally classified into sub-genres which describe the sexual fantasy which the film and actors attempt to create. Am Abend , one of the earliest pornographic films that have been collected at the Kinsey Institute for Research in Sex, Gender, and Reproduction, starts with a female masturbation scene.