Lying face down one may use the hands, one may straddle a pillow, the corner or edge of the bed, a partner leg or some scrunched-up clothing and hump the vulva and clitoris against it. When used as an alternative to penile-vaginal penetration, the goal may be to preserve virginity or to prevent pregnancy. Cum shots typically do not appear in girl-girl scenes and orgasm is normally implied by utterances, cinematic conventions, or body movement. The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place. Top and dominant are widely recognized for those partner in the relationship or activity who are, respectively, the physically active or controlling participants. Medical pornography involves sexualized medical, often fake, including gynecological pelvic examinations, rectal examinations, and pelvic or gynecological ultrasounds. Some pornographic films use an artificial semen substitute to simulate or enhance creampie shots. To avoid soreness from this resulting friction, some may prefer to use a personal lubricant, masturbation cream or saliva during masturbation. Reality and voyeur pornography, animated videos, and legally prohibited acts also influence the classification of pornography. In the gay pornography industry, which uses amateurs as well as professional actors, the term gay-for-pay refers to actors labeled or believed to be straight but who engage in same-sex sexual activities for money. Studies among BDSM practitioners in the US have shown that about half of all men find the idea of bondage to be erotic; many women do as well. The industry generally hot gay sex refers to such films as adult films, which is part of adult entertainment. These actors often play the top roles big tit milf but this is not always the case, such as with Kristen Bjorn and some Bel Ami models. Such documents have not been recognized as being legally binding, nor are they 3d hentai intended to be. Contrary to the other two types, B/D does not define the Tops and Bottoms itself, and is used to describe the general activities with either partner being the receiver and the giver.