Cultural history of the buttocks desirability of buttocks: Since the early 2000s, songs about the female buttocks have proliferated, especially in the hip-hop, reggae/dancehall, and R&B genres. Buttocks are often emphasized in pornography. Patricia Hill Collins, an African-American post-modern feminist writer, theorizes that this is derived from a stereotype that black women are promiscuous, and their buttocks are objectified by pornography as a result. A buttocks fetish or buttocks partialism refers to a condition wherein the buttocks becomes a primary focus of sexual attention. It may be associated with coprophilia, panty fetishism, eproctophilia, and sadomasochistic corporal punishment involving the buttocks. "Pygophilia" refers to sexual arousal
Sexual arousal and firm, the skin of the scrotum is pulled tighter, and the testes are pulled up against the body. However, the relationship between erection and arousal is not one-to-one. After their mid-forties, some men report that they do not always have an erection when they are sexually aroused. Equally, a male erection can occur during sleep (nocturnal penile tumescence) without conscious sexual arousal or due to mechanical stimulation (e.g. rubbing against the bed sheet) alone. A young man — or one with a strong libido — may experience enough sexual arousal for an erection to result from a passing thought,