It just happened.
Motor Mouth asked how babies come out.
I told him the doctor takes the baby out of the Mommy's Vajayjay. Motor Mouth pointed to himself and asked to know specifically where it came out. I had to point to myself and show him (clothed). He then asked what happens to the mommy's vajayjay 'after'. I told him it opens for the baby and then goes back to normal.
And now, he wants some milk and for me to lay down with him so he can go to sleep.