|This secret waterfall is where the kid goes to try out new material that may one day become part of her expression repertoire.|
Welcome to the world of stock expressions. I have a few of my own as well -- "Hey you kids get outta the yard!" (You can image the squinty eyes and flared nostrils).
But as serious amateurs and academics know, these stock expressions are the result of careful cultivation and actual minutes of practice.
Check out the kid as she puts the finishing touches on an expression that she has come to reply upon.