I interviewed for a security position where they asked me an interesting question (I don't exactly remember what it was). After thinking a bit I told them "you

I interviewed for a security position where they asked me an interesting question (I don't exactly remember what it was). After thinking a bit I told them "you don't" — as in there isn't a solution to the problem they posed. They shook their heads and admitted that as best as they could tell there wasn't a solution but they wanted to see if they missed anything. I got the job.