Erotic spankings are commonly combined with other forms of sexual foreplay. The introduction of the home video and Internet saw a boom in the worldwide porn industry that generates billions of dollars annually. The term is typically used by the cinematographer within the narrative framework of a pornographic film, and since the 1970s has become a leitmotif of the hardcore genre. Sadism describes sexual pleasure derived by inflicting pain, degradation, humiliation on another person or causing another person to suffer. Internationally, hentai is a catch-all term to describe a genre of anime and manga pornography. Works in this genre may explore philosophical, political or social issues. Coprophilia , also called scatophilia or scat , is the paraphilia involving sexual arousal and pleasure from feces. The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place. In contrast, a celebrity may take the route of openly releasing the tape and benefit directly from royalties as well as indirectly from the publicity. Shotacon : Similar to Lolicon, this genre involves prepubescent or under-aged boys between the ages 6–12. Certain websites have begun providing bondage videos and photographs featuring the kidnapping roleplay, which has been largely the hallmark of detective style bondage magazines. Studies have found that masturbation is frequent in humans of both sexes and all ages, although there is variation. The purpose of this kind of agreement is primarily to encourage discussion and negotiation in advance, and then to document that understanding for the benefit of all parties. As a form of non-penetrative sex, it can be done for its own enjoyment or as foreplay. The use porn milf of gay fuck the word creampie to describe such scenes originated in U. Additionally, the buttocks give an indication of the shape and size of the pelvis, which impacts reproductive capability. Breeding is sometimes followed by felching, which 3d hentai involves sucking the semen from the partner anus.