In pornography, depictions of lesbian sex form a popular subgenre, directed toward a male heterosexual and female homosexual audience. Hentai is the various forms of Japanese pornography, including H-manga, H-anime, and H-computer games. While bondage is a very popular variation within the larger field of BDSM, it is nevertheless sometimes differentiated from the rest of this field. Softcore gay pornography also exists; it at one time constituted the genre, and may be produced as beefcake pornography for heterosexual female and homosexual male consumption. These scenes may either have the cameraman directly engaging in sex or merely filming others having sex. Saliva pornography involves salivation and saliva. 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. Celebrity sex tapes are amateur or professionally-made recordings of sex acts, as performed by a celebrity and their partner. It may be used as foreplay, or as an alternative hentai videos to sexual penetration. The term is a slang word that originated in the gay community and comes from the equestrian term bareback, which refers horny milfs to the practice of riding a horse without a saddle. As in B/D, the declaration of the Top/Bottom may be required, though sadomasochists may also play without any Power Exchange at all, with both partners equally in control of the play. This style of filming is in contrast to having a separate, third-person camera crew filming all the action. Animal masturbation has been observed in many species, both in the wild and in captivity. There is also some evidence that pornography can be used to treat voyeurism. Mutual masturbation can be practiced by males or females 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. First found in softcore movies and erotic thrillers, depictions of lesbianism gay sex video entered ma celebrity porn instream cinema in the 1980s.