Probably wasn't the best, but its a funny question to be asked;
I give you a glass jar, a penny, and a cork. I put the penny into the jar and seal the jar with the cork. Remove the penny from the jar without taking the cork out.
Fermi Questions are pretty useful if you need to gain an understanding of a candidates ability to process their own thoughts in an uncomfortable situation.
It depends on how you define 'best'. Do you mean the most humorous, most obscure or are you referring to non-tech questions that reveal a lot about your candidate?
I love that question, and now I use it now whenever I interview people. You can tell pretty quickly whether you can relate to someone depending on how they answer it.
A funny question to ask, is if they know what a 418 HTTP error code is.
I've never been asked a good non-technical interview ? in an interview for a technical position, but the best non-technical ? I was ever asked was for a summer job cutting grass at a golf course.
I give you a glass jar, a penny, and a cork. I put the penny into the jar and seal the jar with the cork. Remove the penny from the jar without taking the cork out.
I'll reply with answer if no one can get it :P