"You did eat me!"

Last night while putting Aidan to bed he pointed to a picture of me pregnant with him.  He asked what the picture was and this was our conversation:

Aidan:  "Now let's look at the pictures.  What's that Mom-mom?"  (points to the picture)
Me:  "That's Mama and Dada and baby Aidan in Mama's belly."
Aidan:  "I don't like the belly."
Me:  "Why don't you like the belly?"
Aidan:  "I'm too big."
Me:  "Well yes, you are too big.  But when you were a tiny little baby you were in my belly.  And then you came out."
Aidan:  "I pee out your penis Mom-mom?"
Me:  "Not quite."

This morning he wanted to talk about babies in bellies again.

Aidan:  "Now tomorrow I go in your belly?"
Me:  "No.  You were only in my belly one time, when you were a tiny little baby."
Aidan:  "You did eat me!"
Me:  "No buddy, I didn't eat you."
Aidan:  "Now you can go in Aidan's belly?"
Me:  "No, I'm too big to go in your belly."
Aidan:  "Now Dada can go in my belly?"
Me:  "No.  Dada is too big too."
Aidan:  "Baby sister is a little tiny baby."
Me:  "Yes, she is.  She was in Mama's belly too, but she came out."

Something tells me that we're not done talking about this and he's really confused.  How is it that babies are in bellies if you don't eat them?  How do they come out?  Did Mama really eat him?  Will he eat a baby and then pee it out? 

Ahhhh!  He's not even three and it has started already!!!  And we're not even pregnant!