Joke stolen from: Training2Laugh

At a family picnic, my aunt was admonishing her six-year-old son to wash his hands before eating. He protested that they weren't dirty, though after a few minutes of complaining, the boy finally did go and wash them.

Later, while they stood in line for the condiments to add to their hamburgers, the boy dropped his food on the grass. He stood whimpering at his mother's side until she told him, "Oh, pick it up! A little dirt never hurt anyone."