My kids are teenagers so fortunately I don't see this face anymore. In this diaper commercial from Australia, I was taken back to my days as a young parent.

When you are a new parent and your baby gets "that look" on his face at first you think he is smiling at you. Then you realize that it is not a happy look that is generated because he is glad to see you. That happy look comes from the baby expressing relief at filling his diaper. I know it isn't the most palatable subject but it still will make most  parents remember when. I think the happiest day of my parental life was when I finally could quit buying diapers. Ahh memories.