I've got an interesting story. I was 10 years old, living in what was then the Soviet Union. Pornography was illegal then, and mere possession was considered a sex offense punishable by several years of jail time. Still, some boys in my school managed to get some somewhere, and it was being secretly passed around. It was amateurish, black-and-white shots printed on photo paper. Mostly women posing, spreading their legs, and inserting various objects into their pussies. I've never seen anything like it before and it really turned me on. So that was the first time I masturbated to a picture.