Little Johnny - Chemisty Set               

              Little Johnny took his new chemistry set down to the basement 
     where he stayed all afternoon mixing various liquids together.  
     Eventually, his dad went down and found him surrounded by test tubes, 
     pounding something into the wall. "Why are you hammering a nail into 
     the wall?" asked the dad.  "It's not a nail," said Johnny.  "It's a 
     worm!  I tried to bring this worm back to life with my special chemical 
     mixture, but my formula  made the worm hard as a rock."
              Johnny showed his dad the liquid mix that he had soaked the 
     worm in, and his dad said, "I'll tell you what.  You give me the test 
     tube with your special chemical mixture in it and I'll buy you a 
     Toyota." So little Johnny handed the test tube over.
               The next day, when Johnny got home from school, he saw a 
     brand new Mercedes-Benz parked in the driveway.  He then asked his dad 
     about the car.
               "Oh," said the father, "your Toyota is in the garage.  The 
     Mercedes is from your mother."