For much of the history of cinema and television, lesbianism was considered gaysex taboo, though since the 1960s it has increasingly become a genre in its own right. If one person is penetrated by two objects, it is generically called double penetration . Multiple men and women Bisexual pornography features one woman and two men who all perform sex acts on each other. Clothed male, naked female is one-sided female nudity in which one or more females are nude while one or more men are clothed. Mammary intercourse is known as titty-fucking, titfuck, or a titjob in the United States, as well as tit wank or French fuck in the United Kingdom - the latter term dating back to the 1930s; while a more jocular equivalent is a trip down mammary lane. Bondage pornography specializes in the depiction of sexual bondage or BDSM activities as photographs, stories, movies, or drawings. The volume of semen that is ejaculated depends on several factors, including the male health, age, degree of sexual excitement, and the time naked milf since his last ejaculation. It is typically animated pornography, as the legal age to be featured in a pornographic film in Japan is 18. Incest itself hentai videos is largely taboo, and is a crime in many countries. Most bisexual porn is made by small production companies rather than the major studios. Oral sex pornography frequently features a person performing fellatio, and less frequently cunnilingus. In the gay pornography industry, which uses amateurs as well as professional actors, the term gay-for-pay refers to actors labeled or believed to be straight but who engage in same-sex sexual activities for money. They further argue that setting a discrete line between safe and not-safe activities ideologically denies consenting adults the right to evaluate risks vs rewards for themselves; that some adults will be drawn to certain activities regardless of the risk; and that BDSM play—particularly higher-risk play or edgeplay—should be treated with the same regard as extreme sports, with both respect and the demand that practitioners educate themselves and practice the higher-risk activities to decrease risk.