Voyeur pornography may also include shots of topless women on topless beaches who are unaware of the cameras but may legally be photographed due to the public setting. Women who perform in lesbian pornography often do not consider themselves lesbian or bisexual. Dwarfs or midget pornography features performers who gay hentai are dwarfs/midgets. Bear features a combination of middle-aged, hairy or overweight males. When used as an alternative to penile-vaginal penetration, the goal may be to preserve virginity or to prevent pregnancy. A pornographic work is characterized as hardcore if it has any hardcore content, no matter how small. If dramatic skills are not involved, a performer in a porn film may also be called a model. This makes varying degrees of stimulation an integral part of oral sex for many men. Multiple men and women Bisexual gay sex video pornography features one woman and two men who all perform sex acts on each other. Cuckold fetish pornography lesbian milfs that involves a cuckolded husband. Sub-genres can also be classified into the characteristics of the performers or the type of sexual activity on which it concentrates, and not necessarily on the market to which each sub-genre appeals. John Stagliano is considered to have started the gonzo pornography genre with his Buttman series of films. Common positions include lying on back or face down, sitting, squatting, kneeling or standing. These actors often play the top roles but this is not always the case, such as with Kristen Bjorn and some Bel Ami models. For much of the history of cinema and television, lesbianism was considered taboo, though since the 1960s it has increasingly become a genre in its own right. Bondage/BDSM Bondage pornography features performers tied up or constrained in various ways. The term BDSM dates back to 1969; however, the origin of the term BDSM is unclear and is believed to have been formed either from joining the term B&D with S&M , or as a compound initialism from B&D, D&S , and S&M. Stimulating the prostate from outside, via pressure on the perineum, can be pleasurable as well.