Some anthropologists and sociobiologists believe that breast fetishism derives from the breasts similarity to buttocks, but instead provide sexual attraction from the front of the body. Bear features a combination of middle-aged, hairy or overweight males. There is, however, no third party camera work involved. Studies have found that masturbation is frequent in humans of both lesbian milfs sexes and all ages, although there is variation. Reality and voyeur pornography, animated videos, and legally prohibited acts also influence the classification of pornography. Patricia Hill Collins, an African-American writer, theorizes that this is derived from a stereotype that those of black descent are promiscuous, and their buttocks are objectified by porn as a result. While wearing diapers, a diaper fetishist videos gays generally experiences a comforting feeling. Since mammary intercourse is a non-penetrative sex act, the risk of passing a sexually transmitted infection that requires direct contact between the mucous membranes and pre-ejaculate or semen is greatly reduced. Clothed male, naked female is one-sided female nudity in which one or more females are nude while one or more men are clothed. Real school shots or videos which are sexualized may violate hentai porn privacy laws in some countries. The term is typically used by the cinematographer within the narrative framework of a pornographic film, and since the 1970s has become a leitmotif of the hardcore genre. 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. Lesbian pornography typically features a wider range of appearances and body types than is typical of mainstream pornography. Clothed female, naked male pornography features naked men and clothed women; typically, the women humiliate and abuse the men or perform fellatio and/or handjobs on the men.