How a Berkeley Eccentric Beat the Russians–Then Made Useless, Wondrous Objects

> Ribet recalls seeing his first Klein bottle at the home of a colleague and deciding he wanted one. “I phoned Cliff the next morning and said something like ‘I’m a mathematician, and I want to buy a Klein bottle.’ Cliff replied with a question: ‘If tin whistles are made out of tin, what are fog horns made out of?’ I was speechless for a tiny moment and then replied, ‘fog.’ There was a pause; then Cliff said, ‘You are a mathematician!’”

So this was a fun anecdote in the story, but my immediate reaction (ex-physicist that I am) was, "But of course everyone would say 'fog', wouldn't they?"

I immediately asked two people, and they both looked puzzled and said nothing.

Is this actually a good distinguishing test? Please, HN, try this on your friends and see if it's true!