The line is heavy and carries authority of a parent. It was the thought that both the parents were thinking of when their son barged in their on going conversation. Though unspoken, the gesture that both the parents made made it clear what they were thinking about exactly the same thing. When a parent talks of how disciplined a child must be. The capitalization highlights the stress laid on the words. They are unsaid by the parent, however they are authoritative implying that a child ought to be obedient and well behaved.
