why does scout decribe Walter cunningham's life situation to her teacher?

Ms. Caroline wants to lend Walter some money for lunch. Walter is livid. Scout interrupts and explains how the Cunninghams work. Walter comes from a proud family. Although they live in relative poverty, they refuse to borrow money.

At first, all Scout says is, "He's a Cunningham." In Maycomb County, that is enough for everyone to understand, because everyone has a reputation. However, Miss Caroline is not from Maycomb County, so the explanation makes no sense to her. THEN Scout has to explain the "they don't take charity" reputation.