From the mouths of babes...

Me: "Lily, would you like to have a little brother or sister?"
Lily: "the baby will be in your belly?" as she pats my stomach
Me: "yep, the baby will live in my belly until it is ready to come out and play with you"
Lily: "can I ride the baby?"
Me: "no honey, but you can play with him or her but you have to be gentle"
Lily: "no, that's okay, I want a bike"