Often other friends and community members may witness the signing of such a document in a ceremony, and so parties violating their agreement can result in loss of face, respect or status with their friends in the community. Typically features adult, masculine men with varying degrees of muscle, body fat, and body hair, akin to beefcakes, or bears. The activity is done by itself or as a part of or prelude to other activities which many times involve sex. 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, mature milfs but unequal roles; thus, the idea of informed consent of both the partners becomes essential. The most successful animated features produced in the United States primarily for adult audiences were directed by Ralph Bakshi, including Fritz the Cat, Heavy Traffic and Coonskin. Additionally, the buttocks give an indication of the shape and size of the pelvis, which impacts reproductive capability. The genre presents itself as real couples having real sex. Special forms include erotic roleplay like ageplay, hentai videos in which a difference in age, either real or enacted, formulates the background; young gay porn or petplay. Perhaps following the example set by gay pornography, they have become a popular subgenre within heterosexual pornography since the turn of the century, featuring both vaginal and anal ejaculations. Cartoon pornography includes, but is not limited to, hentai and parody renditions of famous cartoons and comics. It is geared towards heterosexual men, who most typically define a threesome as such. The initialism BDSM includes psychological and physiological facets: Bondage & Discipline Dominance & Submission Sadism & Masochism Types of Play This model for differentiating among these three aspects of BDSM is increasingly used in literature today. Masturbation is the self-sexual stimulation of the genitals for sexual arousal or other sexual pleasure, usually to the point of orgasm.