Consent is the most important criterion here. The term discipline describes psychological restraining, with the use of rules and punishment to control overt behavior. In addition to mainstream pornography, the popularity of facials has led to creation of its own niche market, like video series that specialize in showing the act. In some societies, the terms fox, plum, chick, or chicken are preferred. The term soft crush refers to the more common fetish surrounding videos involving inanimate objects or small invertebrates being crushed, while the term hard crush refers to such videos involving larger animals with vertabrae, and arguably more pain-susceptible animals . It is mutual consent that makes a clear legal and ethical distinction between BDSM and such crimes as sexual assault or domestic violence. One or more of the participants may engage in autoerotic sexual activity, such as masturbation, possibly without physical contact with the other participants. One-sided male nudity can also arise when a male disrobes as part of a male striptease. Interracial pornography typically employs ethnic and racial stereotypes in its depiction of performers and many of interracial pornographic films still include racial stereotypes, although the segregation of actors by race has diminished considerably. Fisting involves the 3d hentai insertion of one partner entire hand into a vagina or the anal cavity. As of 2013, little analysis of this paraphilia has been reported in medical literature. Internal ejaculations, followed by images of semen dripping from the anus, are sometimes depicted in bareback gay pornography, where they are referred to by the term breeding or the reverse money shot. Bisexual DVDs sell much better online than in adult video stores, possibly due to customers in stores feeling embarrassed gay sex video to buy them. Well-known female porn stars who expressed their pleasure in pegging their male partners include Taylor Wane, Debi Diamond, Brittany Andrews, gay group sex and Monique Covét. Softcore pornography generally contains nudity horny milfs celeb sex tapes or partial nudity in sexually suggestive situations, but without explicit sexual activity, sexual penetration or extreme fetishism, while hardcore pornography may contain graphic sexual activity and visible penetration, including unsimulated sex scenes.