Gang bang pornography is a type of pornography that depicts an individual engaging in physical sexual activity with multiple partners sequentially or at once. Exhibitionist pornography features performers, usually female exposing themselves in public and spans simple flashing to public sex. It may involve sexual attraction to women who are pregnant or appear pregnant, attraction to lactation, gay movies or attraction to particular stages of pregnancy such as impregnation or childbirth. Strictly speaking, bondage means binding the partner by tying their appendages together; for example, by the use of handcuffs or by lashing their arms to an object. Scenes of multiple penetration are common in pornography. Some couples use a threesome as a way to develop a love triangle . For other diaper fetishists, simply wearing a diaper, the bulking feeling and crinkling sounds associated with it, is enough to cause the fetishist a form of erotic pleasure or sexual arousal. Anti-pornography psychologist Ana Bridges and colleagues conducted a content analysis of best-selling heterosexual pornographic videos showing that over 96% of all scenes concluded with a male performer ejaculating onto the body of his female partner. High heel pornography involves women or men dressed in high heeled shoes. Some productions are noted for sophisticated hentai movies and/or experimental storytelling and animation techniques. In many cases, that person is also aroused by smelling body parts that have a urine scent. Foot fetishism, foot partialism, foot worship, or podophilia is a pronounced sexual interest in feet. Rough sex pornography is similar to pornography featuring sadomasochism, and typically features lesbian milfs a Top who humiliates and/or degrades a Bottom while being physically violent towards them. This type of stimulation is typically all that is required to achieve orgasm and ejaculation. However, sex researchers and adolescent health care professionals have found no evidence for the existence of rainbow parties, and as such attribute the spread of the stories to a moral panic.