Number One

Setting: Max, Emma, and Dad are traveling somewhere in the minivan. Emma is looking out the window.
Emma: "Dad, the birds are doing number one!"

Dad hesitates before responding. He contemplates where Emma may have learned about "number one". He contemplates how she could possibly see birds "doing number one" from a moving minivan. Then he finally realizes that the three of them had witnessed Canadian Geese flying in formation about a week before. In that formation one side of the "V" formation was much shorter than the other. It made it look like the number 1.