When I played little league and high school football we had this one activity we did called "The Door". Essentially, it was a piece of plywood stuck in the ground so that you could not see who was on the other side of it. We broke into two lines and you just ran full speed around the door not knowing who you were about to smash into. The teams and coaches essentially cheered when someone got a "stinger". That was when you got hit so hard that your head felt like it was getting stung by a bee...I often wonder what effects that kind of stuff has had on my life.