When I was a lot younger, I had neighborhood friends who were older than me. The most 'enlightening' and sensual experience of my young life was one day when we were hanging out in the 'shed' we used as a 'club house', and the older girls somehow got one of the older boys (a tall skinny 'tough kid' named Monte) to masturbate in front of us!
At the time, I had never even seen a penis (in person), much less a hard one, and knew nothing about 'ejaculation'. All I remember is that he dropped his drawers right in front of us, took it out, played with himself until he was hard and sticking straight out and then masturbated.
I had no idea a boys dick got that big, and remember being totally amazed and turned on with what I was seeing for the first time. The older girls were telling him to 'make it cum' (whatever that meant?), which he soon actually did! I found out what 'cum' was, as a large amount of Monte's shot onto the floor in front of us!
I recall being amazed and totally turned on! It was a show that never got repeated but one that certainly educated me and 'accelerated' my own sexual activity.