The gay group sex Silent Duck, momsex also called Duck-Billing, toon porn is the technique often used in which the person engaging in hand insertion shapes the hand to resemble a duck beak. It is used, for example, at fertility clinics to stimulate sperm donors. Normal quantities of ejaculate range from 1.5 to 5.0 milliliters . For example, in Australia it is rated Refused Classification . Foot fetish pornography features heavy emphasis on the feet of the participants, either in combination hentai videos with kissing mobile porn sites and genital sex or in the context of acts such as trampling or crush fetishism. Interracial pornographic films have experienced an explosion in popularity, becoming one of the fastest-growing and biggest-selling genres. Reflective of its views on sexuality and culture, Japanese pornography delves into a wide spectrum of heterosexual, homosexual, and transgender sexual acts in addition to unique fetishes and philias. Ass to mouth pornography shows the transfer of a performer penis from a second performer anus to that same second performer mouth in a single shot. Tentacle rape or shokushu goukan is found in some horror or hentai titles, with tentacled creatures having sexual intercourse with female characters. Hardcore pornography is pornography that depicts penetration or extreme fetish acts, gay twinks or both. Although interracial pornography theoretically can apply to depictions of sexual activity between performers of any different racial groups, the term is most commonly used for heterosexual sex acts between black and white performers. The term applies to the depiction of the act rather than the act itself, and so does not include live exhibitions like sex shows and striptease. Reality pornography is professionally made porn which seeks to emulate the style of amateur pornography. The term combines elements of the Freudian psychoanalytic fetish and the Marxist commodity fetish, and is used in the context of British, Spanish and hentai porn videos French colonialism and imperialism and their aftereffects. It is also known colloquially as gushing or squirting, although these are considered to be different phenomena in some research publications.