The strange things is, despite all the crap we used to get up to, I can't ever remember anyone getting even mildly hurt.
I remember bumps and bruises and having to get an ambulance once cos someone broke a leg*, but that was it and we did some daft stuff. Kids were made by tonka** in the 70s.
*Near my house we had some woods, bordering the woods was a dry beck and a cornfield. After the farmer cut the corn we used to pinch the hay and fill the beck with it. We used to then pretend we were Lee Majors in The Fall Guy and jump out of the tree and land in the piled up hay. A few 'I dare you's' later and we were jumping from 20ft up. It was all going swimmingly until one lad missed the hay pile ......
**Another 70s throwback :)