when I was in elementary school–5th grade, I believe–I was walking down the hall to get a drink and I saw some 2nd grader running down the hallway super fast.
now, since I was that one kid who always tried to enforce rules even though I had no authority, I said to the kid, “No running in the halls!”
the kid looked at me and asked, “Why not?”. then he slammed face-first into the wall.