To Pete, the end of the world is beginning to look like a very good thing. And all the better if it comes before Monday--before the test and before the substitute teacher blames him for the incident with the aquarium or for stealing his large and overly friendly dog, Mishmash. How pete slves his problem wih Mishmash and the substitute teacher is a story that will tickle any young reader who has ever had difficulties with test, and dogs.