How about home made slingshots,  frying a few ants with our magnifying glass or jumping the creek after a rain. Seeing who could leave the longest skid mark on the sidewalk with their mustang bicycle. Swinging as high as you could and then jumping off or spending the day on a merry-go-round. Boys and girls exposing themselves to each other with innocent snickering  and without any consequence to their actions. Jumping through the girls skipping rope, playing cowboy and indians without offending anyone but the crabby old lady next door. Peeking into windows and running off, sliding across  frozen ponds or jumpimg on thin ice. There was a day recently during a beautiful summer afternoon when I noticed there were no kids playing outside and I asked my wife where are all the neighborhood children... she said...probably playing nintendo or something! ........sad but true.