Who taught this child?

Who taught my two year old to say "nana nana boo boo" and laugh hysterically? Because he has been doing it for the last week, any time he is being naughty (and he knows it!)

I caught him up on the kitchen counter yesterday with a bottle of children's Tylenol in his hot little hand (used a bar stool to climb up on the cupboard and then reached for the top shelf.) He turned to me with his hands on his hips and said "I need Tylenol." O-kaaaaay, then.

Today, he followed me to the basement and back up again. I asked him to close the door behind him...which he did. Unfortunately, he locked it in the process. Now, some may say he did this on accident. Or just out of curiosity. I DON'T THINK SO! We had an incident with his 7 year old brother doing the same thing just a couple of days ago and he witnessed the trouble Mitchell got for doing it. He did it ON PURPOSE. Oh yeah, "nana nana boo boo" followed. (The basement door requires a key. Our house key fits, but will not turn. We have to remove the hinges and the door to rectify the problem.)

I believe he was named correctly. Max. As in the main character of Where the Wild Things Are. For he is the wildest thing of all...