Two years ago when my son was ten he brought up the subject of where babies came from. So, after a few moments of sheer panic, I sat him down and told him the basics.
He looked at me for a few seconds in consideration and then asked for some clarification on just where things were supposed to go. "Part of the daddy goes inside the mommy?"
"That's right," I told him.
"This part?" he asked, gesturing at the part in question.
"Yes."
His brow furrowed and then he looked at me like I had lost my mind. He spread his hands in bewilderment and plaintively asked, "But how?!?"
There was only one way to answer that: "Ask me again when you're older."
He still hasn't asked - thank goodness.