It's expected that you stand up for your significant other.
Charlie is at a party with his wife Karen, when one of the guests, Frank says Karen is fat.
Charlie wants to respond to Frank's statement.
Charlie tells Frank that he can't talk about his wife that way unless he want's to rumble.
Charlie tells Frank that it's true, Karen is fat and could stand to lose some weight.
Karen is delighted that Charlie is defending her honor against the insulting stranger.
Karen is not only insulted by her weight being discussed  but is also angry with Charlie for agreeing with Frank.