Gumball sets out to prove to Penny's father that he's good enough for his daughter. Gumball decides that the best way to prove to Mr. Fitzgerald that he's good enough for Penny is to become his apprentice for the day. The problem is, Mr. Fitzgerald has an important interview and Gumball's enthusiastic attempts to help him might actually do more harm than good, both to Mr. Fitzgerald's business and to Gumball's future with Penny.