Bart joins the karate class after being impressed by its advertisement. When he attends the class he is disappointed when he found out he'd have to work hard and study to get good. So instead he skips the classes after Homer drops him off. This later comes back to Bart as Lisa calls upon Bart to protect her from some bullies - Jimbo, Kearney and Dolph. However, since he did not actually attend class, he was brutally defeated.