1.   In San Francisco, lilacs are a sure-fire conversation stopper.

2.   His comment was a conversation stopper.

3.   Four thousand goose-grazing hours an acre are not to be bandied about lightly as a conversation stopper.

4.   For many people, checking Web sites acts as a conversation stopper that is bound to worsen with the proliferation of Internet-enabled phones and hand-held computers.

5.   In these books, history and tradition are not conversation stoppers, not concepts to be invoked with a respectful hush.

6.   It was a conversation stopper.