Professor A at Harvard told the following story, supposedly a first hand account of his student days at Chicago, though it never struck me as remotely plausible. (I think he just told it so that he would seem like a teddy bear in comparison.) But I wonder if anyone else has heard variants of this.
At the beginning of a course, Professor X would start asking some reasonable questions, the answers to which students taking the course could be expected to already know. Finally, he would ask one unfortunate student a question which no one taking the course would be able to answer. Upon the student's failure to answer correctly, Professor X wouldn't explain that the student's ignorance was justified, instead letting this event undermine the student's confidence about taking the course. Professor X would continue to single out this poor target for humiliation until he or she finally dropped the course. Professor A claimed to believe that Professor X's motivation was to have lit a fire under the remaining students and make them band together.
Again, it's a rather unlikely tale of abuse. Though perhaps with a plant "student" playing along as the victim it could be an effective ploy ...
