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. Double Stuffed , Double Vaginal , or Double Anal pornography involves the penetration of one orifice by two penises or other objects. Some men also enjoy anal stimulation, with fingers or otherwise, without any prostate stimulation. Among swinging couples, one of the two partners is often the driving force and the other is more passive-supportive of the addition of additional sex parties. Yaoi is anime or manga that features videos gays gay males . Examples of mentally oriented practices are education games, during which the dominant requires certain forms of behavior from the submissive. John Stagliano is considered to have started the gonzo pornography genre with his Buttman series of films. The cover can have hinges or be a separate part. Felching is a sexual practice involving the gay hentai act of orally sucking semen out of the vagina or anus of one partner. Rape pornography features performers simulating rape. Some pornographic films use an artificial semen substitute to simulate or enhance creampie shots. These actors often play the top roles but this is not always the case, such as with Kristen Bjorn and some Bel Ami models. In the fetish cuckolding subculture, it is most common for the female to take on the sexually dominant role and the male the submissive role, however, female subs, sometimes referred to as cuckqueans, also exist. If dramatic skills are not involved, a performer in a porn film may also be called a model. Internationally, hentai is a catch-all term to describe a genre of anime and manga pornography. The activity is done by itself or as a part of or prelude to other activities which many times involve sex. Cum shots typically do not appear in girl-girl scenes and orgasm porn milf is normally implied by utterances, cinematic conventions, or body movement. Femdom features BDSM scenes in which the dominant partner is female.