A couple years ago a friend of mine mentioned that he had known another mutual friend of ours for many years, much longer than I would have guessed. I asked him "what does he do?" and he thought for a moment before saying "you know ... I have no idea, it has never come up".

Definitely one of his more interesting qualities.

I don't know if this is acceptable in the US, but I always found it distasteful when people ask about your job 30 seconds into meeting you. I think it's much more polite to talk about generic stuff until jobs or skills come up naturally. Sometimes, they just never do, and that's fine. Need to know!