What does scout do to make calpurnia furius?What lesson does calpurnia teach her?

Jem invites Walter Cunningham over for lunch when he finds out that the boy doesn't have any food. Walter hesitates but then takes Jem up on the friendly offer. At the Finch house, Atticus and Walter discuss farming, and Scout is overwhelmed by their adult speech. Walter asks for some molasses and proceeds to pour it all over his meat and vegetables. Scout rudely asks him what he's doing and Calpurnia gives her a lecture in the kitchen about how to treat guests - even if they're from a family like the Cunninghams.