 Bart gets into a fight with Nelson Muntz , the school bully , while defending Lisa and the cupcakes that she baked for Miss Hoover 's birthday party . Nelson beats up Bart after school and warns him to expect the same treatment the following day . At home , Marge consoles and encourages Bart to reason with Nelson . Homer urges Bart to bend the rules and fight dirty . Taking Homer 's advice , Bart does so , but is beaten up again . Bart turns to the toughest member of the Simpson family , Grampa Simpson , who introduces Bart to Herman , the crazed one @-@ armed proprietor of an army surplus store . He instructs Bart on military tactics , then Bart declares war on Nelson and his sidekicks . 
