All you need to do is download the License to be a Kid and sign it. Then you can be a kid again. Of course if you get grounded, tied up or subjected to wedgies that is your problem. So wah! Tell the guys who posted it in the first place!
Well, it is official. By signing in the space provided you will "no longer be subject or beholden by tall or demanding persons". Furthermore, you will also no longer be "responsible for anyone’s actions but your own."