Tell me about your favorite bug.
I ask this because it's a hugely open ended question, and almost no one has thought about it beforehand. It's amazing the different responses I get, and just how illuminating they are. People talk about:
- how they can't think of anything (for the record, this is a bad sign).
- how very very many there are (also a bad sign - you really can't differentiate?).
- who found the bug (was it them alone? a team? did they really take the lead here? was it a customer and you did the after-the-fact diagnosis?).
- what's important about a bug to them (hugely visible GUI issue? funny but embarrassing problem? subtle issue that shows how smart and thorough they are?)
- why that problem stuck with them (a recent thing that was the first that popped into their head? - not generally good, by the way)
I find this a good opening for conversation, and it can lead in all sorts of directions. Plus, it's nice to get people off a well-rehearsed path.
What do you ask in your interviews?