The big tit milf term lesbian is also used with regard to sexual identity or sexual behavior, regardless of sexual orientation, or as an adjective to characterize or associate nouns with female homosexuality or same-sex attraction. Lesbianism has been a theme in erotic art since at least the time of ancient Rome, and many regard depictions of lesbianism to be erotic. It is commonly depicted in pornography, but very rarely in mainstream cinema. Tentacle rape or shokushu goukan is found in some horror or hentai titles, with tentacled creatures having sexual intercourse with female characters. Amateur porn has been called one of the most profitable and long-lasting genres of pornography. The buttocks in human females thus contain more adipose tissue than in males, especially after puberty. Pegging is a sexual practice in which a woman performs anal sex on a man by penetrating the man anus with a strap-on dildo. Hentai is the various forms of Japanese pornography, including H-manga, H-anime, and H-computer games. Bisexual DVDs sell much better online than in adult video stores, possibly due to customers in stores feeling embarrassed to buy them. Going back at least as far as the Christy twins in the 1970s, depictions gay cock of incest and particularly incest between twins has been a feature of gay pornography. Twink pornography features younger performers, and usually features young men under 30 who identify as gay or bisexual. Generally, interest differs between people, and gender depends on sexual orientation. 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. Mutual masturbation can be practiced by males or females in pairs or groups with or without actually touching another person as indicated by hentai sex the following examples of contact versus non-contact scenarios: Non-contact mutual masturbation Two people masturbating in the presence of each other but not touching. Interracial pornographic films have experienced an explosion in popularity, becoming one of the fastest-growing and biggest-selling genres.