Unlike the usual power neutral relationships and play styles commonly followed by couples, activities and relationships within a BDSM context are often characterized by the participants taking on complementary, but unequal roles; thus, the idea of informed consent of both the partners becomes essential. Some people get sexual pleasure by inserting objects, such as urethral sounds, into the urethra , a practice known as urethral play or sounding. The loose and direct camera work often includes tight shots of the genitalia, unlike some traditional porn. Studies among BDSM practitioners in the US have shown that about half of all men find the idea of bondage to be erotic; many women do as well. As a form of non-penetrative sex, it can be done videos gay for its own enjoyment or as foreplay. New York photographer Irving Klaw also published illustrated adventure/bondage serials by fetish artists Eric Stanton, Gene Bilbrew, Adolfo Ruiz and others. The study also found that participants reacted positively to a much wider range of figures than a control group, even rating emaciated figures higher. Production of such films was profitable, and a number of producers specialised in their production. This type of pornography is almost exclusively hentai, as true hermaphroditic humans are not fertile and are not usually found in nature. Exhibitionism: Becoming noticeably desperate or wetting oneself with the express purpose of being seen by strangers. The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place. In Japan, point of view pornography is referred to as hamedori . While some fantasize about a giantess who is slightly taller than himself, others are interested in giantesses that are hundreds or even thousands of feet tall. Cartoon pornography is the portrayal of illustrated or animated fictional characters in erotic or sexual situations. Mammary intercourse has sometimes been considered a perversion.