Works in this genre may be considered gay bear porn adult for any number of reasons. Contrary to the other two types, B/D does not define the Tops and Bottoms itself, and is used to describe the general activities with either partner being the receiver and the giver. It is also followed by dedicated industry publications and trade groups as well as the mainstream press, private organizations , government agencies, and political organizations. A study of 164 males in Finland from two SM clubs found that 18.2% had engaged in coprophilia; 3% as a sadist, 6.1% as a masochist, and 9.1% as both. 18% of heterosexuals and 17% of homosexuals in the study pool had tried coprophilia, showing no statistically significant difference between heterosexuals and homosexuals. The loose and direct camera work often includes tight shots of the genitalia, unlike some traditional porn. Sadism describes sexual pleasure derived by inflicting pain, degradation, humiliation on another person or causing another person to suffer. Mutual masturbation, mutual manual stimulation of the genitals between partners, can be a substitute for sexual penetration. The term pearl necklace is used by some because the drops of semen deposited by the man resemble a necklace of translucent white pearls. Its gain in prominence has been attributed to its depiction in the film Pecker, which was released in 1998. Macrophilia is a fascination with or a sexual fantasy involving giants, more commonly expressed as giantesses . Internationally, hentai is a catch-all term to describe a genre of anime and manga pornography. Bukkake pornography involves a performer, usually gay hentai female, onto whom several men or women ejaculate, usually on the face. A pornographic work is characterized as hardcore if it has any hardcore content, no matter how small. On May 27, 2010 the television program The Doctors discussed the topic with dozens of teens, parents, and professionals. John Stagliano is considered to have started the gonzo pornography milf fuck genre with his Buttman series of films.