I can kind of see a place for the estimation problems e.g. how many square feet of pizza are sold in the US each year. We are always coming up with project estimations and despite reading all the advice and so forth, long term project estimations can still be about as reliable as the answers to such questions. At least that is a think on your feet sort of thing.

Pretty much all my experiences asking and answering questions has been on the straightforward side though - I'd consider asking how honest someone is to be on the stupid side. Would many reveal themselves to be fundamentally unsound, or play anything except a straight bat to such a question if they wanted a job? The SQL coffee filling one would also not be for me, though I could of course have a stab at a jokey answer as described.

Cultural preferences (e.g. Star Wars vs. Star Trek) could provide some hints though personally I'd be looking for adult rather than children's tastes. I think I have slightly jokingly asked whether candidates prefer Apple or Android devices - without a preference really on my part, but it does indicate whether they value aesthetics over tinkerability.