You shouldn't squeal on people.
Tom notices his wife underpaid her restaurant bill yesterday, but the waitress didn't notice.
Tom wants to let someone know about the underpaid bill.
Tom forgives his wife and only tells his wife about the underpaid bill instead of the restaurant.
Tom calls the restaurant on the phone letting them know that his wife underpaid.
Tom's wife thanks Tom for letting her know and is relieved he didn't make a big deal out of it.
Tom's wife becomes furious at Tom for squealing on her, and feels she doesn't have to explain herself.