Sentence:  A girl who expects her mother to nag her about her untidy bedroom will hear that message, even though the mother may want to talk about something quite different, so a loving invitiation to go shopping that started "When you've finished in your bedroom this morning. . ." might result in the child screaming, storming out and slamming the door because she expected this to be a <WSD>nag</WSD> about the state of the room and didn't let you finish with “ . . . shall we go to the shopping centre?”. 
Meaning of the word marked with <WSD> tags:  A repeated complaint or reminder.