I did it in high school with a friend. Played strip poker, believe it or not, just because we were dumb (or curious) and when both of us were totally naked, we decided to jerk each other, one at a time. Did it a few times with this guy.

Then continued with occassional mutual j/o experiences into adulthood until married. Still remember the excitement of putting my hand around another guys hard, warm boner, and feeling equally excited to get a tug from him.