Little Johnny looked up and replied ?

Finding one of her students making faces at others on the playground, Ms. Smith stopped to gently reprimand the child.
Smiling sweetly, the Sunday school teacher said, “Johnny, when I was a little girl, I was told if that I made ugly faces, it would freeze and I would stay like that.”
Little Johnny looked up and replied, “Well, Ms Smith, you can’t say you weren’t warned.”