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. Some may keep their hand stationary while pumping into it with pelvic thrusts in order to simulate the motions of sexual intercourse. The existence of such content in commercially available pornography is widely considered an urban legend. It is also followed by dedicated industry publications and trade groups as well as the mainstream press, private organizations , government agencies, and political organizations. Bondage websites and 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 lesbian hentai pornographic magazines such as Nugget and Hustler Taboo magazine. Evolutionary psychologists suggest that rounded buttocks may have evolved to be desirable trait because they provide a visual indication of the woman youth and fertility. 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. Threesome can also refer to a love triangle, a three-way romantic relationship. Kurt Wild, who appeared as a bottom in Lucas Entertainment Gigolos, is married to a woman and has three children. The actual height of the giantess within the fantasy may vary depending on the individual. It is geared towards heterosexual men, who most typically define a threesome as such. Solo performances in gay pornography have been described gay bear porn in 1985 as either or both active and/or passive , whereas female solo performances are said to be exclusively passive . 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.