Just who is in charge around here anyway?

"Mommy!! Come look!! I got a skateboard!!" yells Shay through the monitor, 20 minutes into his "nap."  Curiosity piqued, I poke my head into the bedroom, and see that he is standing in his bed on top of a big hardback picture book, arms out for "balance," with a big grin on his face.  "Wow," he says, "that's cool," as though prompting me with how one is supposed to respond. "Wow, Shay, that's cool," I say; "now, go to sleep."  "Shhh," he admonishes me, pointing over at his sleeping sister.  "Be quiet, Mommy; baby sleeping."