For much of the history of cinema and television, lesbianism was considered taboo, though since the 1960s it has increasingly become a genre in its own right. Cuckolding can also be mixed with other non-monogamous relationship arrangements with which it has substantial overlap such as Swinging, wife-swapping, open relationships, and polyamory, etc. Rainbow party A rainbow party is an urban legend spread from the early 2000s. Diaper fetishism is totally independent from pedophilia as the wearer derives pleasure only from the diaper and/or use of it. The reverse hentai movies of this, in which nude women interact with clothed men, is called hot gay sex Clothed male, naked female . Spanking can be administered in a number of spanking positions. The wife who enjoys cuckolding her husband is frequently called a hotwife, or a cuckoldress if the man is more submissive. Men may find stimulation of the anus, rectum, and adjacent organs enjoyable. 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. While anal sex is commonly associated with male homosexuality, research shows that not all gay males engage in anal sex and that it is not uncommon in heterosexual relationships. Softcore gay pornography also exists; it at one time constituted the genre, and may be produced as beefcake pornography for heterosexual female and homosexual male consumption. Multiple men and women Bisexual pornography features one woman and two men who all perform sex acts on each other. Mammary intercourse is a sex act, performed as foreplay or as non-penetrative sex, that involves the stimulation of the male penis by the female breasts and vice versa. Originating in Japan in the 1980s, the genre subsequently spread to North big tit milf America and Europe, and crossed over into gay pornography. Female ejaculation is the expulsion of fluid by the paraurethral ducts through and around the human female urethra during or before an orgasm. Adult animation is genre of animation geared towards adults and sometimes teens.