Little Johnny - I Need a Break 
                
                One day, the teacher walks into her classroom and
      announces to the class that on each Friday, she will ask a question 
      to the class and anyone who answers correctly doesn't have to go to 
      school the following Monday.
                
                On the first Friday, the teacher asks, "How many grains of 
      sand are in the beach?"  Needless to say, no one could answer.
                
                The following Friday, the teacher asks the class,
      "How many stars are in the sky?" and again no one could answer.  
      Frustrated, little Johnny decides that the next Friday, he would 
      somehow answer the question and get a 3 day weekend.
                
                So Thursday night, Johnny takes two ping-pong balls and 
      paints them black. The next day, he brings them to school in a paper 
      bag.  At the end of the day, just when the teacher says, "Here's this 
      week's question," Johnny empties the bag to the floor sending the
      ping-pong balls rolling to the front of the room. Because they are 
      young kids who find any disruption of class amusing, the entire class 
      starts laughing.
                
                The teacher says, " Okay, who's the comedian with
      the black balls?"
                
                Immediately, little Johnny stands up and says,
      "Bill Cosby, see ya on Tuesday!"