Many of these activities might be based on rape. Lesbianism in erotica deals with depictions in the visual arts of lesbianism, which is the expression of female-to-female sexuality. The primary subjects of pornographic depictions are pornographic models, who pose for still photographs, and pornographic actors or porn stars, who perform in pornographic films. Felching is a sexual practice involving the act horny milfs of orally sucking semen out of the vagina or anus of one partner. Point of view pornography is adult entertainment filmed to look as if the watcher were experiencing the sex act themselves. They may be noted for using risqué themes, graphic violence, sexuality or black comedy in a manner that is unsuitable for younger audiences. This technique is also used by some men who gay twinks are circumcised who have excess skin left from circumcision. A heterosexual threesome may involve two men and a woman, or one man and two women - that is, two men having sex with a woman , or two women with a man. Cartoon pornography is the portrayal of illustrated or animated fictional characters in erotic or sexual situations. Shotacon : Similar to Lolicon, this genre involves prepubescent or under-aged boys between the ages 6–12. The two sets of people involved often meet either randomly or arrange to meet up beforehand over the Internet. The volume of semen that is ejaculated depends on several factors, including the male health, age, degree of sexual excitement, and the time since his hentai porn last ejaculation. Such documents have not been recognized as being legally binding, nor are they intended to be. Often other friends and community members may witness the signing of such a document in a ceremony, and so parties violating their agreement can result in loss of face, respect or status with their friends in the community. The Girls Gone Wild series is one example. Unlike the usual power neutral relationships and play styles commonly followed by couples, activities and relationships within a BDSM context are often characterized by the participants taking on complementary, but unequal roles; thus, the idea of informed consent of both the partners becomes essential.