This may relate to fetishes such as voyeurism or cuckolding. The related term twinkle-toes, which implies that a man is effeminate, tends to be used in a derogatory gay bear porn manner. Celebrity sex tapes are amateur or professionally-made recordings of sex acts, as performed by a celebrity and their partner. Hentai is the various forms of Japanese pornography, including H-manga, H-anime, and gay hentai H-computer games. Often, strong views are expressed with regard to anal sex; it is controversial in various cultures, especially with regard to religion, commonly due to prohibitions against anal sex among gay men or teachings about the procreative purpose of sexual activity. 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. It may be used as foreplay, or as an alternative to sexual penetration. In some societies, the terms fox, plum, chick, or chicken are preferred. Mammary intercourse is said by Alex Comfort to produce mutual orgasm in women with sensitive breasts , and it was one of the nine substitute exercises for penetrative sexual activities, as detailed in the Paradis Charnels of 1903. Mutual masturbation can be practiced by males or females mature milfs in pairs or groups with or without actually touching another person as indicated by the following examples of contact versus non-contact scenarios: Non-contact mutual masturbation Two people masturbating in the presence of each other but not touching. Pornography may be presented in a variety of media, including books, magazines, postcards, photographs, sculpture, drawing, painting, animation, sound recording, film, video, and video games. See Gay-for-pay. A somewhat controversial ejaculation control technique is to put pressure on the perineum, about halfway between the scrotum and the anus, just before ejaculating. Related genres include: Amateur pornography originally referred only to pornography produced by amateurs but now also includes professionally made pornography designed to appear as if it were amateur.