Monkey do: open wide

At the doctor’s office today, she asked FrogMonkey to open his mouth so she could count his teeth. He opened it just about big enough to admit a finger but not a flashlight.
She asked him to open wider. He didn’t budge.
Open really big.
Nothing.
Me: “Hey Bean, open your mouth like Papa is about to give you a bite of food.”
He opened his mouth as wide as it could possibly get.