While most tentacle erotica is animated, there are also a few live-action movies. There are many other variations on male masturbation techniques. Along with the penis, the scrotum is sensitive momsex and considered to be an erogenous zone. Some diaper wearers wear their diapers for limited amounts of time, while others prefer to wear them on a 24-hour, seven-day schedule. Hamedori-type videos were produced from the beginnings of Japanese AV in the early 1980s. The effect is to give the viewer the sense that they are experiencing the sex acts that they are watching, as opposed to simply watching others as a voyeur. The Japanese sex industry uses the term Paizuri . A variant of this is known as ATOM or ATOGM where the insertive partner removes his penis from one recipient anus and inserts it into a second recipient mouth. Discipline often incorporates sadomasochistic aspects, though some sadomasochists distance themselves from D/s practices such as punishment. Ethnic pornography is a genre of pornography that features performers of specific ethnic groups, gaysex or depictions of interracial sexual activity. Interracial pornographic films have experienced an explosion in popularity, becoming one of the fastest-growing and biggest-selling genres. For other diaper fetishists, simply wearing a diaper, the bulking feeling and crinkling sounds associated with it, is enough to cause the fetishist a form of erotic pleasure or sexual arousal. Studies indicate that anilingus is a rare sexual practice between women. Kinbaku is a Japanese style of bondage or BDSM which involves tying up the bottom using simple yet visually intricate patterns, usually with several pieces of thin rope . Pornographic films are generally classified into sub-genres which describe the sexual fantasy gay hentai which the film and actors attempt to create. Unlike Yaoi, Bara is normally made by actual homosexual men, for homosexual men, and tends to focus on the more realistic obstacles and challenges that come with being homosexual in Japan.