As of 2013, little analysis of this paraphilia has been reported in medical literature. The first explicit pegging scene is believed to have been in the 1975 pornographic film The Opening of Misty Beethoven. Reflective of its views on sexuality and culture, Japanese pornography delves into a wide spectrum of heterosexual, homosexual, and transgender sexual acts in addition to unique fetishes and philias. The most common type of erotic spanking is administered on the bare buttocks, but can also be combined with bondage, in order to heighten sexual arousal and feelings of helplessness. Gloryhole pornography features women performing fellatio on unidentified men through a small hole made in a bathroom divider. 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. Rape pornography features performers simulating rape. It is suggested that much of the obscurity and the uncertainties about female ejaculation are related to mixing up these two phenomena. Many men who like trans partners of any variety, known as tranny chasers, do not necessarily identify as gay themselves. A male voyeur is commonly labeled Peeping Tom, a term which hentai movies originates from the Lady Godiva legend. Jerk off instruction features a performer encouraging or instructing the viewer to masturbate, often culminating in a countdown at the end of which the viewer is invited to induce orgasm. Actual spying may violate privacy and/or trespassing laws in many countries. Animal masturbation has been observed in many species, both in the wild and in captivity. Shibari is a Japanese word that literally means to tie or to bind. Transgender pornography features performers momporn who cross-dress for sexual gratification, either for themselves or for their partners. Bestiality is illegal in many countries. In general, BDSM play is usually structured such that it is possible for the consenting gay movies partner to withdraw his or her consent during a scene; for example, by using a safeword that was agreed on in advance.