The other person may do the same during or after. Double penetration of the vagina, anus and mouth, can involve: Simultaneous penetration of the anus by two penises or other objects. Pornography is often distinguished from erotica, which consists of the portrayal of sexuality with high-art aspirations, focusing also on feelings and emotions, while pornography involves the depiction of acts in a sensational manner, with the entire focus on the physical act, so as to arouse quick intense reactions. A survey by the New York City Department of Health and Mental Hygiene found that heterosexual women are more likely to bareback when engaging in anal sex than homosexual and bisexual men. Bondage/BDSM Bondage pornography features performers tied up or constrained in various gayporn ways. The object or situation of interest is called the fetish; the person who has a fetish for that object/situation is a fetishist. Pornographic films are typically categorized as either softcore or hardcore pornography. Diaper pornography involves performers wearing diapers, sometimes with an adult performer acting in the role of a caretaker. Double Stuffed , Double Vaginal , or Double Anal pornography involves the penetration of one orifice by two penises or other objects. Sadomasochism is practiced in isolation relatively rarely, though some masochists report biting, pinching, or even stun-gunning themselves as a prelude to, or as part of, masturbation. The prostate gland is one of the organs that contributes fluid to semen. Omorashi: The act of holding one own urine until the need to urinate is urgent, making another hold in their urine, or watching another person with an urgent need to urinate. Transsexual porn star Wendy Williams has stated that transsexual Porn is classified as Straight Specialty. Sexologist Alfred Kind suggested that the buttocks is the primary sexual presentation site in primates. The reverse of this, in which nude women interact with clothed men, is called Clothed male, naked female .