The stimulation may involve hands, fingers, everyday objects, sex toys or combinations of these. It is mutual consent that makes a clear legal and ethical distinction between BDSM and such crimes as sexual assault or domestic violence. Many men who like trans partners of any variety, known as tranny chasers, do not necessarily identify as gay themselves. The buttocks in human females thus contain more adipose tissue than 3d hentai in males, especially after puberty. Within a BDSM or D/s context, naked milf facesitting can be an especially intense form of erotic humiliation. The nipples are erogenous zones, and vigorous stimulation of them during masturbation usually causes the penis to become erect more quickly than it would otherwise. It is sometimes described as a sexual fantasy, by women or men, depicting an exhibitionist or physique worship scenario. Fisting involves the insertion of one partner entire hand into a vagina or the anal cavity. There is also some evidence that pornography can be gay bear porn used to treat voyeurism. Most soft crush fetishists avoid being placed under the same label as hard crush fetishists, believing that crush films with larger animals give the entire group a bad label. Although pornography has usually focused on heterosexuality, due to the prevalence of the heterosexual orientation, explicit gay material has a long history as well, which reaches back to Greek antiquity, if not to prehistory. In the context of consensual erotic activities, sadism and masochism are not strictly accurate terms; there is a significant difference from the medical or psychological usage of both terms. 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. Mammary intercourse is said by Alex Comfort to produce mutual orgasm in women with sensitive breasts , and it was one of the nine substitute exercises for penetrative sexual activities, as detailed in the Paradis Charnels of 1903.