This Is Going To Be Harder Than I Thought

Since I got to hear the heartbeat and am feeling strangely optimistic (did I just say that?), I decided to try to explain to my little Hurricane that he is going to be a big brother.
I sat down on the floor in front of him and showed him a picture (ok, it was a weak-ass drawing I did) of a woman (yes, that was a woman. She was wearing a dress. Sort of) and in her belly was a baby (it was passable).
He looked at it and then at me, one eyebrow raised. This is his father's expression. Usually meant to convey "crazy woman alert".
"She has a baby in her belly!"
Again, look at the picture, look at me. Still crazy.
"Dat's baby?"
"Yes. That's a baby."
He looked doubtful.
"Dat's doggy."
Great. Now I have an art critic on my hands.
New tactic.
"Mommy has a baby in her belly." I gently rubbed my belly and waited.
"I haff baby in bebly Mamas." He lifted his shirt and smiled at me.
"No, mommy has a baby in her belly. Your belly is full of goldfish and tickles."
"No."
"Baby in Mamas belly."
"No. Baby in my bebly."
Hmmm. I guess it is a bit much to expect him to understand at this point but I didn't think he'd be so argumentative either.
"You get to be a big brother just like you have a big sister! We're going to have a baby!"
At this he threw himself into my lap and declared, "I da baby!"

With any luck, we'll get this figured out before the baby gets here.