Although pornography has usually focused on heterosexuality, due to the prevalence of the heterosexual orientation, explicit gay material has a long history as well, which reaches back to Greek antiquity, if not to prehistory. A celebrity may allow such a recording to surface willingly, nude milfs as part of a publicity stunt. A variation on this is to place the fingers and thumb on the penis as if playing a flute, and then shuttle them back and forth. 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. Rape pornography features performers simulating rape. Reality pornography is professionally made porn which seeks to emulate the style of amateur pornography. Transgender pornography features performers who cross-dress for sexual gratification, either for themselves or for their partners. This may relate to fetishes such as voyeurism or cuckolding. Some techniques which may work for one individual can be difficult hot gay sex or uncomfortable for another. 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. Originating in Japan anime hentai in the 1980s, the genre subsequently spread to North America and Europe, and crossed over into gay pornography. A somewhat controversial ejaculation control technique is to put pressure on the perineum, about halfway between the scrotum and the anus, just before ejaculating. Women porn is often produced by women and aimed specifically at the female market - rejecting the view that men are turned on by porn but women only by a box of chocolates. Transsexual pornography is a genre of pornography. Transsexual porn star Wendy Williams has stated that transsexual Porn is classified as Straight Specialty. Currently, animated television series aimed at adults are some of the most popular and critically acclaimed forms of entertainment.