Cooper! UNLOCK THE DOOR!

Why does Cooper get so much pleasure from rushing to the car, getting in, then locking the doors? Tonight at the babysitter's, he beat me to the car and locked me and Evan out. We stood out in the cold, helpless, as he tried to unlock the door. He spilled my glass of tea in the process, and there were little wet and muddy footprints everywhere when we finally got inside. Good times.