Marvin Redpost: Why Pick on Me?. Book 2 - Rejacketed, Paperback/Louis Sachar

Everyone is laughing at Marvin Redpost. He's the grossest kid in school. Why? He picks his nose. Well, that's the rumour the class bully, Clarence, started and no one argues with Clarence - not even Marvin's so-called best friends. So what can Marvin do to turn things round?