Many years ago (1970) all us lower-6th form pupils - they didn't call us 'students' in those days - were invited to take the old O-level General Studies examination. We were told that the school refused to teach the subject, because it was so easy, but we were welcome to take the exam if we wanted to. This was without any preparation whatsoever! (We weren't even told what was on the syllabus, so we couldn't prepare on our own, even if we wanted to!). We all took the exam and I think we all passed. (I certainly did, anyway!). I'm still not really sure what it was that we were being tested on but it still counts as one of my 10 O-levels. (I wish that they were all that easy!).
Chris