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. In some societies, the terms fox, plum, chick, or chicken are preferred. It is suggested that much of the obscurity and the uncertainties about female ejaculation are related to mixing up these two phenomena. Comic books often featured characters being tied up and tying others up, particularly in damsel in distress plots. Other possibilities are possible, such as a man having sex with two women who are having sex with each other. Tentacle rape or shokushu goukan is found in some horror or hentai titles, with tentacled creatures having sexual intercourse with female characters. The work of Bruce Seven has been called reality porn, due to his lack of using scripts and asking his performers to act naturally in their own character. This may help them develop their orgasm, increase its pleasure, and may inspire them to masturbate on a more frequent basis. The term applies to the depiction of the act rather than the act itself, and so does videos gay not include live exhibitions like sex shows and striptease. The term is a slang word that originated in the gay community and comes from the equestrian term bareback, which refers to the practice of riding a horse without a saddle. In addition to mainstream pornography, the popularity of facials has led to creation of its own niche market, like video series that specialize in showing the act. Originating in Japan in the 1980s, the genre subsequently spread to North America and Europe, and crossed over into gay pornography. Sex parties may be organized to enable people to engage in casual sexual activity or for swinging couples or people interested in group sex to meet, but any gathering where sexual activity is anticipated can be called a sex party. In some scenes or relationships it may be impossible for consent to be withdrawn in the middle of a scene, or the bottom may have the ability to revoke consent for a relationship as a whole, but not for a particular scene.