Kirby Kelvin just can’t help it. He keeps cracking up in class. No matter how hard he tries, his imagination runs away with him and his giggles spill out “ like root beer foaming out of a bottle.” Kirby’s teacher, Mr. Frost, has had enough. She sends Kirby to Mr. Gloomsmith’s office for not-laughing lessons. Mr. Gloomsmith is as gloomy as can be, and his not-laughing lessons work like a charm---until irrepressible Kirby turns the table as only a cut-up can!