Women who perform in lesbian pornography often do not consider themselves lesbian or bisexual. There has been an increase in discussion and portrayal of masturbation in art, popular music, television, films, and literature. Bisexual pornography is a genre of pornography which most typically depicts one woman and two men who all perform sex acts on each other. Some straight actors have started acting in gay porn only to be accused of being gay while others first step was to strictly do solo scenes. Sexual relations between women have been illustrated as well as narrated, but much of the written material from the early modern lesbian hentai period has been destroyed. The prostate gland is one of the organs that contributes fluid to semen. There may be more than two participants; both group videos gays sex and gang banging can be included. In human sexuality, a threesome is sexual activity that involves three people at the same time. Lying face down on a comfortable surface such as a mattress or pillow, the penis can be rubbed against it. The phrase buttered bun is sometimes used to refer to the owner of the orifice in question. Hardcore pornography is pornography that depicts penetration or extreme fetish acts, or both. Foot fetishism has been defined as a pronounced sexual interest in the feet or footwear. Originating in Japan in the 1980s, the genre subsequently porn milf spread to North America and Europe, and crossed over into gay pornography. Detective magazines, comic books and early fetish magazines In the early 20th century, Detective magazines covertly provided a way of publishing bondage imagery. Comic books often featured characters being tied up and tying others up, particularly in damsel in distress plots. Rape pornography features performers simulating rape. Some may keep their hand stationary while pumping into it with pelvic thrusts in order to simulate the motions of sexual intercourse. Double Stuffed , Double Vaginal , or Double Anal pornography involves the penetration of one orifice by two penises or other objects.