A father came home and asked where his son was. His wife replied that he was downstairs playing with his new chemistry set. The father was curious, so he wandered downstairs to see what his son was doing. As he walked down the steps, he heard a banging sound. When he got to the bottom he saw his son pounding a nail into the wall. He aid to his son, "What are you doing? I thought you were playing with your chemistry set. Why are you hammering a nail into the wall?"

His son replied, "This isn't a nail, Dad, it's a worm. I put these chemicals on it and it became as hard as a rock."

His dad thought about it for a minute and said, "I'll tell you what, Son, give me those chemicals and I'll give you a new Volkswagen."

His son quite naturally said, "Sure why not."

The next day his son went into the garage to see his new car. Parked in the garage was a brand new Mercedes. Just then his dad walked in. He asked his father where his Volkswagen was. His dad replied, "It's right there behind the Mercedes. By the way, the Mercedes is from your mother."