Heh. My now-ex was a preschool teacher*, and for several years we had only one car, so I would drop him off and pick him up at the day-care center. My stock response to being asked which kid was mine was, "Oh, I'm not old enough to have a child here." Even though I was usually older than the person asking. :-)

* And one of the reasons I married him was that he was very firm about liking to be with the kids during the day, but wanting to be off duty when he went home.