Related genres include: Amateur pornography originally referred only to pornography produced by amateurs but now also includes professionally made pornography designed to appear as if it were amateur. Interracial pornographic films have experienced an explosion in popularity, becoming one of the fastest-growing and biggest-selling genres. Omorashi: The act of holding one own urine until the need to urinate is urgent, making another hold in their urine, or watching another person with an urgent need to urinate. A variant of A2M is ATOM where a performer inserts his penis directly from one recipient anus into a second recipient mouth. Softcore gay pornography also exists; it at one time constituted the genre, and may be produced as beefcake pornography for heterosexual female and homosexual male consumption. The work of Bruce Seven black gay porn has been called reality porn, due to his lack of using scripts and asking his performers to act naturally in their own character. Though there have been numerous gang bang pornographic films since the 1980s, they usually involved no more than half a dozen to a dozen men. Some do not use the diapers at all, for arousal, or bladder and bowel movements. The term discipline describes psychological restraining, with the use of rules and punishment to control overt behavior. The term Asiaphile is sometimes used to describe the same phenomenon as is yellow fever . The original definition of dogging – and which is still a closely related activity – is spying on couples having sex in a car or other public place. Cuckold fetish pornography that involves a cuckolded husband. This may help them develop their orgasm, increase its pleasure, and may inspire them to masturbate on a more frequent basis. The concept of lesbian, to differentiate women with a shared sexual orientation, is a 20th-century construct. Throughout history, women have not had the same freedom or independence to pursue homosexual relationships as men, but neither have they met the same harsh punishment as homosexual men in some societies.