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. To tea bag is a slang term for the sexual act of a man placing his scrotum in the mouth of a willing sexual partner for pleasure or onto the face or head of another person. In straight pornography, intercourse is often followed by a facial, pearl necklace or other visible ejaculation. When all regions of the face are included, facial cum shots comprise approximately 62% of scenes where external ejaculation occurs. The sub-genres usually conform to certain conventions, and each may appeal to a particular audience. The fundamental principles for the exercise of BDSM require that it should be performed with the informed consent of all involved parties. Softcore pornography generally contains nudity or partial nudity in sexually suggestive situations, but without explicit sexual activity, sexual penetration or extreme fetishism, while hardcore pornography may contain graphic sexual activity and visible penetration, including unsimulated sex scenes. In gay pornographic movies, actors who identify themselves as heterosexual, but who nevertheless perform explicit sexual acts with other males on film do not face the same stigmas as the mainstream acting counterparts and indeed can rise quickly to being featured actors. Pornography is generally classified as either softcore or hardcore pornography. Freud, however, considered such extensions of sexual interest to fall within the range of the normal, unless marked out gay hentai by exclusivity . Felching involves drinking recently ejaculated hot gay sex semen from the vagina or anus. For other scenes, particularly in established relationships, a safeword may be agreed to signify a warning rather than explicit withdrawal of consent; and a few choose not to use a safeword mature milfs at all. 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.