I had a full professor in engineering school who would do stuff like that. Also, on his exams, wrong answers subtracted from your score, so it was possible to get a negative grade on an exam (many students did), and with only three exams in the semester that would wreak havoc on your average. He was brought out of retirement to help weed students out of the program at the junior level. His was the only course I failed (I got a D), and when I retook it I made an A with virtually no study time, so I knew the material. That was 38 years ago and I am still angry about it.