I did shut up a couple of PHBs who were showing pictures of their yachts, bragging about their length and features. I know all sorts of nonsense like they can make them longer and longer, but have to keep the width down to save of parking fees.
The bit that shut them up was saying I get sea sick on anything that small.
OK, I've been passenger on a big ferry, but they think everyone has their own boat.
I think this would be a good time to mention that you are a keen coin collector, and ask if you can have one of his for your collection. With any luck, his conceit will stop him noticing the scrap value of the coin he is being asked to hand over.