However, bisexual pornography is often placed near the gay section in adult video stores, since many consumers are gay men. It is also known colloquially as gushing or squirting, although these are considered to be different phenomena in some research publications. Foot fetishism has been defined as a pronounced sexual interest in the feet or footwear. The term pearl necklace is used by some because the drops of semen deposited by the man resemble a necklace of translucent white pearls. For much of the history of cinema and television, lesbianism was considered taboo, hentai videos though since the 1960s it has increasingly become a genre in its own right. Common positions include lying on back or face down, sitting, squatting, kneeling or standing. It is sometimes combined with BDSM features. Sexual orientation Pornography features an increasing variety of combinations of actors by their sexual orientation such as lesbian, gay, bisexual, and transsexuals in addition to traditional heterosexual roles. Double gay twinks penetration of the vagina, anus and mouth, can involve: Simultaneous penetration of the anus by two penises or other objects. Tentacle erotica can be consensual, but frequently contains elements of non-consensual sex. Sadomasochism is practiced in isolation relatively rarely, though some masochists report biting, pinching, or even stun-gunning themselves as a momporn prelude to, or as part of, masturbation. As of 2013, little analysis of this paraphilia has been reported in medical literature. There are number of types of sex parties: Swinger party/gathering A swinger party or partner-swapping party is a gathering at which individuals or couples in a committed relationship can engage in sexual activities with others as a recreational or social activity. Group sex most commonly takes place in a private sex party or semi-public swinger gathering, but may also take place at massage parlors or brothels or, in some jurisdictions, at purpose-built locations such as sex clubs. The full-weight body-pressure, moisture, sex odors and darkness can be perceived as powerful sexual attractions or compulsions.