New York photographer Irving Klaw also published illustrated adventure/bondage serials by fetish artists Eric Stanton, Gene Bilbrew, Adolfo Ruiz and others. Mutual masturbation, mutual manual stimulation of the genitals between partners, can be a substitute for sexual penetration. Commenting on why there are not as many female macrophiles, psychologist Helen Friedman theorized that because women in most societies already view men as dominant and powerful, there no need for them to fantasize about it. His most famous model was Bettie Page, who became the first celebrity of bondage film and photography. In these research publications, it is suggested that real female ejaculation is the release of a very scanty, thick, and whitish fluid from the female prostate, while the squirting or gushing shown frequently in pornography is a different phenomenon, the expulsion of clear and abundant fluid, which has been shown to be a diluted fluid from the urinary bladder. Content featuring male bisexuality has been a growing trend since the advent of internet pornography. A 2009 study found that heterosexual male fat admirers preferred hentai porn females that were clinically overweight and rated both overweight and obese women more positively than slighter individuals. The most common male masturbation technique is simply to hold the penis with a loose fist and then to move the hand up and down the young gay porn shaft. Tentacle erotica can be consensual, but frequently contains elements of non-consensual sex. Voyeur pornography may also include shots of topless women on topless beaches who are unaware of the cameras but may legally be photographed due to the public setting. Real school shots or videos which are sexualized may violate privacy laws in some countries. Shotacon : Similar to Lolicon, this genre involves prepubescent or under-aged boys between the ages 6–12. Internal ejaculation shots are a comparatively milf fuck recent development in pornography; they are not found in early pornographic films. Some aspects of the research community distinguish between female ejaculation and what is colloquially known as squirting or gushing.