Some years back I was working in a project that essentially dealt with all things related to foreigners and foreign affairs in Switzerland. You could manage entry visas, work permits, citizenship, international warrants, Interpol requests, etc.

One of the test managers (from client side - i.e. the government) was once manually "testing" and mixed up the production and test instance, to both of which he was logged in at the time.
The test case then ended up setting up an entry ban against himself, as he used his own name for testing...

Next time he returned from vacation the border control at the airport were like "Uhm, Sir, we can't let you into the country. Please come with us." :D :D

(He managed to clear that up in end, I dare say, though, that he learned his lesson.)