Little Johnny was sitting on a park bench munching on one chocolate bar after another. After the sixth one an elderly man sitting on the bench across from him  said, "Son, you know eating all those sweets isn't good for you. It will give you acne, rot your teeth and make you fat."
Little Johnny replied, "My grandfather lived to be 107 years old."
The man asked, "And did your grandfather eat six chocolate bars at a time?"
"No," replied Little Johnny, "but he knew how to mind his own business!"