My brother and I jack off with neighbor boys in our barn from early age.
Saw my brother -- 18 months older many times --- I recall his shooting his first load.
I saw older boys at our old swimming pool in the creek that went through our farm. I recall how big the high school boys looked jacking off, to me a grade school boy.
In 4-H all the boys would go skinny dipping in May when we had the first meeting for the summer. there was no sex play then.