The teacher noticed that Johnny had been daydreaming for a long time, so she decided to get his attention. “Johnny,” she said, “if the world is 25,000 miles around and eggs are sixty cents a dozen, how old am I?”
Johnny answered, “Thirty-four.”
The teacher replied, “Well, that’s not far from my age. Tell me … how did you guess?”
“Oh, there’s nothing to it,” Johnny said. “My big sister is seventeen and she’s only half-crazy.”