Bukkake videos are a relatively prevalent niche in contemporary pornographic films. This yields a view that would not be obtainable directly through the eyes of a person while experiencing the sex act. The term also refers to the visible seeping or dripping of semen from the vagina . Voyeur or peeping Tom pornography is usually more staged with the subjects aware of the cameras, sometimes momsex openly including this exhibitionist awareness. One is in a vertical side of the box for the neck of the person who has their head inside the smotherbox. Some productions are noted for sophisticated and/or experimental gay twink porn storytelling and animation techniques. Big Beautiful Woman is a euphemism for an overweight woman and is frequently used in the context of fat fetishism. The fundamental principles for the exercise of BDSM require that it should be performed with the informed consent of all involved parties. In D/S, the Dominant is the Top and the submissive is the Bottom. The Japanese sex industry uses the term Paizuri . While most tentacle erotica is animated, there are also a few live-action movies. Masturbation has been depicted in art since prehistoric times and is mentioned and discussed in very early writings. However the genre remains a very small proportion of the pornographic DVD market; for example at porn retailer HotMovies. In the attempts of circumvent this type of censoring , actors and producers have featured subject matter unseen or rarely depicted in western pornography. Ethnic pornography is a genre of pornography that features performers of specific ethnic groups, or depictions of interracial sexual activity. High heel pornography involves women or men dressed in high heeled shoes. A threesome is a form of group sex, but involving only three gay hentai people. 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.