This video perfectly demonstrates what happens when you decide to mess about on perfectly innocent playground apparatus. Someone will come a cropper and it will be painful.
This is clearly a worldwide activity. Climb on a swing when someone else is on it and proceed to swing it higher and higher until the original occupant craps their pants.
Thankfully there is, it would seem, a system in place whereby the universe dishes out punishment for those acting like tossers. And this guy gets a double lesson for his trouble.
My only wish is that the other guy being a douchebag had received a similar comeuppance, but he gets away with it relatively unscathed. The only lasting memory for him will be the sound of his friend’s head being struck by metal.