It is sometimes combined with BDSM features. Urolagnia is a form of salirophilia in which sexual excitement is associated with the sight or thought of urine or urination. The concept of lesbian, to differentiate women with a shared sexual orientation, is a 20th-century construct. Bondage websites and big tit milf bondage imagery in mainstream pornography As of 2003, specialist bondage magazines were mostly displaced by the availability of bondage material on the World Wide Web, and the presence of bondage imagery in mainstream pornographic magazines such as Nugget and Hustler Taboo magazine. Examples of mentally oriented practices are education games, during which the dominant requires certain forms of behavior from the submissive. Though gay hentai there have been numerous gang bang pornographic films since the 1980s, they usually involved no more than half a dozen to a dozen men. Transsexual gay cock pornography is a genre of pornography. Lolita pornography features women who are 18 years old or slightly older, who pretend to be underage teen girls. Pornography in Japan is large and intertwined business of adult entertainment with unique characteristics that readily distinguish it from western pornography. Use of the agreed safeword is seen by some as an explicit withdrawal of consent. If dramatic skills are not involved, a performer in a porn film may also be called a model. The term pearl necklace is used by some because the drops of semen deposited by the man resemble a necklace of translucent white pearls. The most common type of erotic spanking is administered on the bare buttocks, but can also be combined with bondage, in order to heighten sexual arousal and feelings of helplessness. Pregnancy fetishism is a context where pregnancy is seen by individuals or cultures as an erotic phenomenon. Irrespective of the legal or social view of pornography, it has been used in a number of contexts. The term Asiaphile is sometimes used to describe the same phenomenon as is yellow fever . As of 2013, little analysis of this paraphilia has been reported in medical literature.