That turned into a lecture from me on how his body actually grew bigger, and he grew from a baby into a big boy. That was nice. Then he asked about how he got out of his mother, when he was born.
It wasn't quite the How Are Babies Made lecture, but it was close. I told him that inside a woman, there was a part of her body called the uterus, and that's where a baby grows if she's having a baby, and then when it's time for the baby to come out, there's a special place that's made for the baby to come out by.
"What's the name of that?"
Since he'd asked it in the context of childbirth, I figured the best, least confusing name was "the birth canal". It's a good, solid, adult name for the body part, and it emphasises the birth function of the anatomy. His mother is what I'd call highly uncomfortable about the topic of sex, and especially the idea of him learning about sex too soon, so I wasn't about to introduce any advanced concepts. I went on to the placenta, and especially the umbilical cord, and I tied it all off with how the place where that was attached eventually turns into the bellybutton. His bellybutton.
I figure that he comes to me with this stuff because I'm the one who's good at giving long-winded scientific lectures on Just Randomly Anything. Besides that, I was the only one home at the time.
