answer: Jonny's mother thanks Johnny for breaking china so that Grandma keeps Jonny busy cleaning instead of herself.
documents: #Person1#: Johnny, I want to thank you.
  #Person2#: What do you mean, Mom? For breaking your best china?
  #Person1#: Oh, Johnny, that stuff was dollar store junk. No, I want to thank you for keeping Grandma busy.
  #Person2#: Well, it's more like she kept me busy. . .
  #Person1#: I know, and normally she's trying to tell me how to clean my house. So, thank you.
  #Person2#: Am I back in your good books?
  #Person1#: Not only that, but I'm going to buy you that video game after all!