As of 2013, little analysis of this paraphilia has been reported in medical literature. For legal reasons, the vast majority of so-called reality porn involves professional actors and lesbian hentai actresses posing as so-called amateurs. Watersports pornography features sexual activities involving urine, such as golden showers. Since development and pronunciation momsex of the buttocks begins at menarche and declines with age, full buttocks are also a symbol of youth. Rape pornography features performers simulating rape. Although pornography has usually focused on heterosexuality, due to the prevalence of the heterosexual orientation, explicit gay material has a long history as well, which reaches back to Greek antiquity, if not to prehistory. The term Asiaphile is sometimes used to describe the same phenomenon as is yellow fever . It like associating every Christian with the zealots who cause religious wars. Performers are usually clean-shaven, thinner and more effeminate than ones in mainstream gay pornography. The definition clash also appears with the English definition of yuri as any lesbian relationship, as opposed to its sexually explicit definition in Japan. The arousal from being desperate comes from the sensation of having a full bladder. Sex parties may be organized to enable people to engage in casual sexual activity or for swinging couples or people gay twinks interested in group sex to meet, but any gathering where sexual activity is anticipated can be called a sex party. The term lesbian is also used with regard to sexual identity or sexual behavior, regardless of sexual orientation, or as an adjective to characterize or associate nouns with female homosexuality or same-sex attraction. Usually that person prefers to stage the wetting so that his/her legs become soaked with urine. Greater economic and social freedom allowed them gradually to be able to determine how they could form relationships and families. This may relate to fetishes such as voyeurism or cuckolding. Several hundred exclusively pegging films were produced, as well as twice as many bisexual and straight films with strap-on scenes.