I tend to think of myself as a huge Geography buff and there's usually no obscure part of the world that I'm not well up on. It's a large part of my job (and a busman's hobby) to know the world and all its cities, regions, counties and geopolitics.
Then a question came up on Pointless the other night asking for the capital of Liberia. My wife said "isn't it Monrovia?" to which I confidently (and wrongly) replied "nah, Monrovia is a little country in its own right I think".
Mrs C was right of course, she scored 6 points, and I've temporarily lost my Geography Expert badge, replaced with the Dunce hat for at least a week I reckon.