Other fetish Bareback pornography features performers who are not wearing condoms. Internal ejaculation shots are a comparatively recent development in pornography; they are not found in early pornographic films. If dramatic skills are not involved, a performer in a porn film may also be called a model. Cuckolding can also be mixed with other non-monogamous relationship arrangements with which it has substantial overlap such gay twink porn as Swinging, wife-swapping, open relationships, and polyamory, etc. 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 shaft. A 2009 study found that heterosexual male fat admirers preferred females that were clinically overweight and rated both overweight and obese women more positively than slighter individuals. 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. Preggo pornography features pregnant performers and may include erotic lactation as a fetish. Some people get sexual pleasure by inserting objects, such as urethral sounds, into the urethra , a practice known as urethral play or sounding. Some masturbate only using pressure applied to the clitoris without direct contact, for example by pressing the palm or ball of the hand against underwear or other clothing. Shotacon : Similar to Lolicon, this genre involves prepubescent or under-aged boys between the 3d hentai ages 6–12. The glans itself may widen and lengthen as the stimulation continues, becoming slightly darker in colour, while the gliding action of the foreskin reduces mature milfs friction. For circumcised males, on whom the glans is mostly or completely uncovered, this technique creates more direct contact between the hand and the glans.