The glans itself may widen and lengthen as the stimulation continues, becoming slightly darker in colour, while the gliding action of the foreskin reduces friction. Female masturbation involves the stroking or rubbing of a woman vulva, especially her clitoris, with an index or middle fingers, or both. The two sets of people involved often meet either randomly or arrange to meet up beforehand over the Internet. Preggo pornography features pregnant performers and may include erotic lactation as a fetish. Cartoon pornography is the portrayal of illustrated or animated fictional characters anime hentai in erotic or sexual situations. It has since become popular enough with couples to be discussed during an episode of Sex and the City. Arcane or occult pornography involves sexualized situations with an occult or magical tone or performers who costume themselves in keeping with the theme, for example, a male performer dressed as a wizard. 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. In some creampie films, both gay and straight, intercourse and internal ejaculation are followed by performers licking up the semen that has dripped from their bodies. Medical pornography involves sexualized medical, often fake, including gay twinks gynecological pelvic examinations, rectal examinations, and pelvic or gynecological ultrasounds. Pornographic films are typically categorized as either softcore or hardcore pornography. However, various groups within society considered such depictions immoral, labelling them pornographic, and attempting to have them suppressed under obscenity laws, with varying degrees of success. Threesome momsex or 3some pornography features one man and two women . Felching is a sexual practice involving the act of orally sucking semen out of the vagina or anus of one partner. Since mammary intercourse is a non-penetrative sex act, the risk of passing a sexually transmitted infection that requires direct contact between the mucous membranes and pre-ejaculate or semen is greatly reduced.