Often happens

Fun story: happend in Switzerland, well not a droptable, but in the state (we call them Kanton) I live in, they introduced a new it system for all schools to use a few years back.

Amongst other things all schools had to register their address with the system and the secretary of the school in the village I live in entered "We don't have one" in the fax number field. Long story short, the db expected an integer, but there where no checks or sanitation in place. Crashed the application for 1 day.