In the 1920s, Havelock Ellis reported that turn-of-the-century seamstresses using treadle-operated sewing machines could achieve orgasm by sitting near the edge of their chairs. It explores the more mental aspect of BDSM. Arguably the most famous example of porn milf the genre is the Taboo series. It may also involve touching, rubbing, or pinching the nipples or other erogenous zones while masturbating. Ethnic pornography is a genre of pornography that features performers of specific ethnic groups, or depictions of interracial sexual activity. When all regions of the face are included, facial cum shots comprise approximately 62% of scenes where external ejaculation occurs. The nipples are erogenous zones, and vigorous stimulation of them during masturbation usually causes the penis to become erect more quickly than it would otherwise. This is commonly called double gay boy porn anal or double stuffing. The Japanese sex industry uses the term Paizuri . They are most often featured with male partners, but are also featured with other transsexuals or cissexual women. It is practiced by people of all sexual orientations, and can be part of a full repertoire of sexual activity. Bukkake, Gokkun, Omorashi, and tentacle erotica are few uniquely Japanese genres known to western viewers. As amateurs in a single segment of a multi-part video, the actresses are typically paid only about 50,000 yen . Jail/Prison/Police pornography involves people in police custody or inmates in jails or prisons in various sexual situations, such as strip searches or body cavity searches. Felching involves drinking recently ejaculated semen from the vagina or anus. POV pornography involves camera angles designed to provide the viewer a view similar to that seen by one of the participants, whose face is never shown. Similar to Freud idea of a fetish, Bhabha defines racial fetish to be a fixation on other races being not different, but lesser or mutilated versions of the white male. It is also often mixed with other fetishes in practice, hentai sex such as voyeurism, denial, etc.