Japanese rope bondage is distinguished by its use of specific katas and aesthetic rules. The anus has a relatively high concentration of nerve endings and can be an erogenous zone, and the receiver may receive pleasure from external anal stimulation. 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. Squirt pornography involves women horny milfs ejaculating. Sexual scenarios may involve male domination, female submission, exhibitionism and erotic entertainment. Said that the female buttocks evolved in the context of females competing for the attention and parental commitment of powerful resource-controlling males as an honest display of fat reserves that could not be confused with another type of tissue, although T. The related term twinkle-toes, which implies that a man is effeminate, tends to be used in a derogatory manner. Real enema shots or videos of true medical situations may violate privacy laws in some countries. As with most forms of sexual activity, anal sex participants risk contracting sexually transmitted infections . Pornography is generally classified as either softcore or hardcore pornography. Along with the penis, the scrotum is sensitive and considered to be an erogenous zone. Facial cum shots are currently regularly gay movies portrayed in pornographic films and videos, often as a way to close a scene. But starting with The World Biggest Gangbang , starring Annabel Chong, the pornographic industry began producing a series of films ostensibly setting gangbang records for most consecutive sex acts by one person in a short period. Given the wide hentai videos range of practices, some of which may be engaged in by people who do not consider themselves as practicing BDSM, inclusion in the BDSM community or subculture is usually dependent on self-identification and shared experience. Men and women may masturbate until they are close to orgasm, stop for a while to reduce excitement, and then resume masturbating.