Following World War II, during a period of social repression when governments actively persecuted homosexuals, women developed networks to socialize with and educate each other. In humans, females generally have more round and voluptuous buttocks, caused by estrogen that encourages the body to store fat in the buttocks, hips, and thighs. Some masturbate only using pressure applied to the clitoris without direct contact, for example by pressing the palm or ball of the hand against underwear or other clothing. Penetration may involve use of fingers, toes, sex toys, or penises. The gay bear porn activity is done by itself or as a part of or prelude to other activities which many times involve sex. The study also found that participants reacted positively to a much wider range of figures than a control group, even rating emaciated figures higher. The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place. There are varieties of definition hentai sex and geographical data presented by organizations and individuals for classifying the Asian people. Cartoon pornography is the portrayal of illustrated or animated fictional characters in erotic or sexual situations. Some pornographic films use an artificial semen porn milf substitute to simulate or enhance creampie shots. The loose and direct camera work often includes tight shots of the genitalia, unlike some traditional porn. The two sets of people involved often meet either randomly or arrange to meet up beforehand over the Internet. Sadomasochistic scenes sometimes reach a level that appear more extreme or cruel than other forms of BDSM—for example, when a masochist is brought to tears or is severely bruised—and is occasionally unwelcome at BDSM events or parties. The term breast fetishism is also used to refer to cultural attention to female breasts and the sexuality they represent, with debate continuing as to whether the modern widespread fascination with breasts among heterosexual males in western societies is a sexual fetish.