When I first told Jake that he would have a sister or brother, and that there is a baby in mama's belly, his first response was "I want to see!" I had to explain that he couldn't see the baby because s/he is in mama's belly and has to grow first. His response? To start digging around in my bellybutton in hopes of seeing the baby that way.
He's excited about the baby, and will occasionally kiss my belly. So sweet.