When I was about 20 I worked at a grocery store, and customers started asking me when I was due. It was really weird because I was terribly skinny and certainly did not look pregnant. (One time I just said, "October" because I was tired of denying it. Strangely enough the person did not ask any other questions.)
Several months later, customers started asking, "How's your son?"
A few years later, I was shopping and a little girl exclaimed, "I know you! You pick up your son from daycare!"
Strangest part, I lived in a pretty small town, so you'd think I would have met this girl who is apparently my twin!