The anus has a relatively high concentration of nerve endings and can be an erogenous zone, and the receiver may receive pleasure from external anal stimulation. Softcore pornography generally contains nudity or partial nudity in sexually suggestive situations, but without explicit sexual activity, sexual penetration or extreme fetishism, while hardcore pornography may contain graphic sexual activity and visible penetration, including unsimulated sex scenes. Body parts including fingers, tongue and penis may be used for anonymous oral, vaginal and/or anal intercourse. Common phrases used to refer to these individuals are chicks with dicks, anime hentai trannies, or shemales, although these are generally considered pejorative slurs among transwomen. A sexual fetish may be regarded as an enhancing element to a romantic/sexual relationship achieved in ordinary ways or as a mental disorder/disorder of sexual preference if it causes significant psychosocial distress for the person or has detrimental effects on important areas of their life. Using the term shemale for a transsexual woman often implies that she is working in the sex trade. In addition to mainstream pornography, the popularity of facials has led to creation of its own niche market, like video series that specialize in showing the act. Buck Angel is the best-known actor in this genre. 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. Sexual scenarios may involve male domination, female submission, exhibitionism and erotic entertainment. Since at least 1973, it has also been used to refer to a sexually attractive young woman. Amateur porn has been called one of the most profitable and long-lasting genres of pornography. Initially, few animation studios in the United States attempted gay twink porn to produce animation for adult audiences, but later examples of animation produced for adults would gain mainstream attention momporn and success.