The most common type of erotic spanking is administered on the bare buttocks, but can also be combined with bondage, in order to heighten sexual arousal and feelings of helplessness. However, various groups within society considered such depictions immoral, labelling them pornographic, and attempting to have them suppressed under obscenity laws, with varying degrees of success. In POV porn, the shooting style is generally similar to gonzo pornography, with the person receiving sexual gratification holding the camera him or herself—aiming it down at the actress or actor who is performing the sex act. Pro-am pornography is sub-genre of amateur pornography that refers to professionally made porn that features amateur actors/actresses, often appearing for the first time in a pornographic film. John Stagliano is considered to have started the gonzo pornography genre with his Buttman series of films. Some may keep their hand stationary while pumping into it with pelvic thrusts in order to simulate the motions of sexual intercourse. The other person may do the same during or after. Oral sex pornography frequently features a person performing fellatio, and less frequently cunnilingus. It is also known colloquially as gushing or squirting, although these are considered to be different phenomena in some research publications. A homosexual threesome would involve either three men or three women. Following gay sex the introduction of the Motion Picture Association of America film rating system, independent animation producers attempted to establish an alternative to mainstream animation. Solo pornography recognized with AVN Awards include the All Alone series and All Natural: Glamour Solos. For some people, non-penetrative sex is the primary sexual activity of choice above all others. Because the viewing of such films carried a social stigma, they were viewed at brothels, adult movie theaters, stag parties, at home, in private clubs and also at night cinemas. Is also common of the furry genre.