Not that it matters anymore since this was pre-Google, but I swear to god, someone actually asked me the manhole cover question when I interviewed at ITA in 2010. This was for a DevOps type role, so maybe they were less well organized on that side of the house.

At first I laughed because I thought he was joking until he I saw he was serious. He followed that up with something about stacking weights on a seesaw.