Fisting pornography features the insertion of an entire hand into a performer vagina or anus. In pornography, depictions of lesbian sex gay video form a popular subgenre, directed toward a male heterosexual and female homosexual audience. Going back at least as far as the Christy twins in the 1970s, depictions of incest and particularly incest between twins has been a feature of gay pornography. Generally, interest differs between people, and gender depends on sexual orientation. Greater economic and social freedom allowed them gradually to be able to determine how they could form relationships and families. Participants usually derive pleasure from this, even though many of the practices—such as inflicting pain or humiliation or being restrained—would be unpleasant under other circumstances. Anal sex or anal intercourse is generally the insertion and thrusting of the erect penis into a person anus, or anus and rectum, for sexual pleasure. Facial cum shots are currently regularly portrayed in pornographic films and videos, often as a way to close a scene. Lucky Pierre is slang for a person performing both receptive and insertive anal and/or vaginal sex simultaneously during a threesome, being positioned between the two partners. Men and women may masturbate until they are close to orgasm, stop for a while to reduce excitement, and then resume masturbating. Pornography is often referred to as porn and a pornographic work as a porno. Facial cum shots are currently regularly portrayed in pornographic films and videos, often as a way to close a scene. In many cases, that person is also aroused by smelling body parts that have a urine scent. This is commonly called double anal or double stuffing. Gonzo porn is influenced by amateur pornography, and it tends to use far fewer full-body/wide shots in favor of more close-ups . Group sex is sexual behavior involving more than two participants. These scenes may either have the cameraman directly engaging in sex or merely filming others having sex.