Isn't there a little brown book Reasoning with the Scriptures that has an entire section on how to rebuff conversation stoppers such as "I am not interested"?
I would delight in reading how you may have used any of these conversation stoppers and how Brian would have responded.
It is a good 15 years but I seem to recall "are you not interested in the God's Word the bible... not interested in JWs?" Etc etc. Would be great to use a conversation stopper on the trolley people just to see if they recognise what you are using on them. Oh the irony!!!