one little comment

Something that somebody says that you must NEVER reply to. That's because they don't want a conversation.

Person 1: I'm sure there are loads of people that smoke who wear jackets like these.
Person 2: Smoking is an addictive habit.
Person 1: Shut up.
Person 2: But you asked me a question/wanted a conversation.
Person 1: No! that was One little comment.