It is geared towards heterosexual men, who most typically define a threesome as such. Evolutionary psychologists suggest that gaysex rounded buttocks may have evolved to be desirable trait because they provide a visual indication of the woman youth and fertility. Some are aroused from wetting their diapers, others like messing their diapers. If dramatic skills are not involved, a performer in a porn film may also be called a model. Diaper fetishism, nappy fetishism or diaperism, is a sexual fetish in which a person feels a desire to wear or use diapers. The full-weight body-pressure, moisture, sex odors and darkness can be perceived as powerful sexual attractions hentai porn or compulsions. It is also known colloquially as gushing or squirting, although these are considered to be different phenomena in some research publications. Felching is a sexual practice involving the act of orally sucking semen out of the vagina or anus of one partner. This genre also features male-on-male fellatio through a small hole made in a bathroom divider. Transsexual porn star Wendy Williams has stated that transsexual Porn is classified as Straight Specialty. 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 niche popularity grew significantly in the latter half of the first decade of the 2000s. Biological anthropologist Helen B. The activity is done by itself or as a part of or prelude to other activities which many times involve sex. A scene where many women have sex with one man is referred to as a reverse gang-bang. Common phrases used to refer to these individuals are chicks with dicks or the derogatory term shemale, although these are generally considered pejorative among transwomen. The act may be carried out face to face, or head to tail, with the woman recommended to be on top if she has smaller breasts. Sigmund Freud considered foot binding as a form of fetishism. People may experience pleasure horny milfs from anal sex by stimulation of the anal nerve endings, and orgasm may be achieved through anal penetration – by indirect stimulation of the prostate in men, indirect clitoral/G-spot stimulation in women, and associated sensory nerves .