I was detained for a couple of hours at Windhoek Airport, Namibia in January because my Visa wasn't in order. Well, I didn't have one. I was told by my employer I didn't need one. I was told by every colleague who had ever been there that a Visa was wholly unnecessary. They were all wrong and if it wasn't for some promises of good behaviour from my customer out there, they would have had me on the next flight out (alternatively, a night in a cell if the last flight of the day had already gone). Fortunately, after a couple of hours, they confiscated my passport and told me I could have it back once I turned up at the airport.

Of course, I was quiet as a mouse and totally polite at all times; unlike some contractors from a partner company who arrived a couple of weeks later with the same problem. They were put onto the next plane out. Apparently, immigration officers at African airports don't appreciate a racist attitude.