When my son was 5, he was visiting my sister and he got really constipated. My sister, ever the panicker, called me to drive 45 miles to the rescue. Whatever. Well, I helped him get straightened out, and we headed home; he was feeling a lot better. While we were driving, he said to me, "Well, at least now I know how it feels to have a baby come out of your butt!" We hadn't gotten into any discussions of babies and anatomy at that time. I don't know where they get this stuff! Probably his little rotten boy-buddies?
To this day, I am still speechless!