Internationally, hentai is a catch-all gay sex video term to describe a genre of anime and manga pornography. This is hentai videos commonly called double vaginal penetration or double stuffing. As well as traditional attraction, the topic also incorporates feederism and gaining, where sexual gratification is obtained via the process of gaining body fat. The cover is open while the submissive lies down on his back and places his head in the box. Works in this genre may be considered adult for any number of reasons. However, gay pornography in the modern world is mostly concentrated in the making of home videos , cable broadcast and emerging video on demand and wireless markets, as well as images and movies for viewing on the Internet. The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place. Many times a top actor will then be sought as a bottom and the debut is often treated as a notable event or even its own release. Unlike the usual power neutral relationships and play styles commonly followed by couples, activities and relationships within a BDSM context horny milfs are often characterized by the participants taking on complementary, but unequal roles; thus, the idea of informed consent of both the partners becomes essential. Special forms include erotic roleplay like ageplay, in which a difference in age, either real or enacted, formulates the background; or petplay. The two sets of people involved often meet either randomly or arrange to meet up beforehand over the Internet. In Japan, point of view pornography is referred to as hamedori . Penetration may involve use of fingers, toes, sex toys, or penises. This technique is also used by some men who are circumcised who have excess skin left from circumcision. The warm sensation felt when urine trickles on the body seems to give very relaxing and pleasurable feelings to the person. As a form of non-penetrative sex, it can be done for its own enjoyment or as foreplay.