Fisting pornography features the insertion of an entire hand into a performer vagina or anus. Sadomasochism does not imply enjoyment through causing or receiving pain in other situations . The interaction between tops and bottoms—where physical or mental control of the bottom is surrendered to the top—is sometimes known as power exchange, whether in the context of an encounter or a relationship. The person sat upon may be in bondage, sexually submissive, or simply held down by the body-weight of the other person. Guro or Gore is a genre of Japanese pornography involving blood, gore, disfiguration, violence, mutilation, urine, enemas, or feces. The Japanese sex horny milfs industry uses the term Paizuri . Such films continued to be produced but could only be distributed by underground channels. Various groups within society have considered depictions of a sexual nature immoral, labeling them pornographic, and attempting to have them suppressed under obscenity and other laws, with varying degrees of success. The anus has a relatively high concentration of nerve endings and can be an erogenous zone, and the receiver may receive pleasure from external anal stimulation. Central to the typical MILF narrative is an age-play dynamic of older women and younger lovers. While most tentacle erotica is animated, there are also a few live-action movies. The 1979 young gay porn U. Reality Reality pornography refers to real or faked amateur encounters. Technically this is a form of exhibitionism rather than group sex per se. Individuals who can change between top/dominant and bottom/submissive roles—whether from relationship to relationship or within a given relationship—are known as switches, though the term switch in this context is occasionally seen as derogatory and is rejected by many who might simplistically fit the definition. The name of the practice, lesbian hentai when it is done in a repeated in-and-out motion, is derived from its passing resemblance to the dipping of a tea bag into a cup of hot water as a method of brewing tea.