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. Can also include auto-fellatio, or performing oral sex on oneself. Ethnic pornography is a genre of pornography that features performers of specific ethnic groups, or depictions of interracial sexual activity. Rough sex pornography lesbian hentai is similar to pornography featuring sadomasochism, and typically features a Top who humiliates and/or degrades a Bottom while being physically violent towards them. They may repeat this cycle multiple times. Teacher and Student or Boss and Secretary pornography involves sexualized situations which take place between an authority figure, such as a teacher or boss, and an underling, such as a student or secretary, often fake. There are currently no known laws forbidding the crushing of objects and insects, however the production or trade of crush erotica involving live vertebrates is condemned by animal rights activists and is illegal in many countries, including gay movies the United States and Great Britain. A glory hole is a hole in a wall, or other partition, often between public lavatory stalls or adult video arcade booths for people to engage in sexual activity or observe the person in the next cubicle while one or both parties masturbate. Freud, however, considered such extensions of sexual interest to fall within the range of the normal, unless marked out by exclusivity . The higher pay scale and profile within a production often leads to group scenes where a straight actor only tops. Individuals who can porn milf change between top/dominant and bottom/submissive roles—whether from relationship to relationship or within a given relationship—are known as switches, though the term switch in this context is occasionally seen as derogatory and is rejected by many who might simplistically fit the definition. In many cases, that person is also aroused by smelling body parts that have a urine scent.