I don't know if it's as psychological as it is physical, but it's extremely uncomfortable. My wife ties my arms and then proceeds to masturbate me.until I come. Instead of stopping, though, she then concentrates on the head of my penis, rubbing and twisting until I'm screaming for her to stop. What makes it psychological is, I know it's coming, but just can't keep myself from ejaculating, because THAT part feels so good. Pain and pleasure