Technically this is a form of exhibitionism rather than group sex per se. The interaction between tops and bottoms—where physical or mental control of the bottom is surrendered to the top—is sometimes known as power exchange, whether in the context of an encounter or a relationship. In September 2003 the BBC reported on the new dogging craze. Some couples use a threesome as a way to develop a love gay twink porn triangle . It can be combined with fellatio and the woman may move her breasts up and down on the penis for an additional stimulation, usually before the man reaches orgasm. Pleasure for the giver during anilingus is usually based more on the principle of the act. It generally contains nudity or partial nudity in hentai videos sexually suggestive situations. Often, slave contracts are set out in writing to record the formal consent of the parties to the power exchange, stating their common vision of the relationship dynamic. It may involve sexual attraction to women who are pregnant or appear pregnant, attraction to lactation, or attraction to particular stages of pregnancy such as impregnation or childbirth. Kinbaku is a Japanese style of bondage or BDSM which involves tying up the bottom using simple yet visually intricate patterns, usually with several pieces of thin rope . In D/S, the Dominant is the Top and the submissive is the Bottom. Transwomen are most often featured with male partners, but are also featured with other horny milfs transsexuals or cissexual women. Pegging is a recently invented word which features a woman penetrating a man with a strap-on dildo. Squirt pornography involves women ejaculating. This scene dynamic may be referred to as consensual nonconsent. In a separate article analyzing 12 men who engaged in bestiality, an additional analysis of an 11-man subgroup revealed that 6 had engaged in coprophilic behavior, compared with only 1 in the matched control group consisting of 12 SM-oriented males who did not engage in bestiality. The Japanese sex industry uses the term Paizuri .