Gay-for-pay describes male or female actors, pornographic naked milf stars, or sex workers who self-identify as heterosexual but who are paid to act or perform as homosexual professionally. The buttocks in human females thus contain more adipose tissue than in males, especially after puberty. It is sometimes described as a sexual fantasy, by women or men, depicting an exhibitionist or physique worship scenario. 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. Creampie scenes depart from heterosexual pornographic convention in favor of a depiction that more closely mimics sexual intercourse as performed in ordinary life; they have been called the counterimage of facials. It is used, for example, at hot gay sex fertility clinics to stimulate sperm donors. Shibari is a Japanese word that literally means to tie or to bind. There were also a very limited number of specialist fetish magazines which featured images of bondage, such as the famous Bizarre magazine published from 1946 to 1959 by the pioneering fetish photographer John Willie, and ENEG Exotique magazine, published 1956-1959. The prostate gland is one hentai sex of the organs that contributes fluid to semen. Entacle erotica describes a type of pornography most commonly found in Japan which integrates traditional pornography with elements of bestiality and a fantasy, horror, or science-fiction theme. Bottom and submissive are widely recognized terms for those partner in the relationship or activity who are, respectively, the physically receptive or controlled participants. A variant of A2M is ATOM where a performer inserts his penis directly from one recipient anus into a second recipient mouth. A pornographic work is characterized as hardcore if it has any hardcore content, no matter how small. Its primary goal is sexual arousal in its audience. There has been an increase in discussion and portrayal of masturbation in art, popular music, television, films, and literature.