On a 100 question multiple-choice test, he would have 15-20 questions in a row with the same answer and it was usually "C." Then he would have patterns - A B C D C B A B C D C B A B C D C B A, etc. I once caught him laughing while watching some of the students furiously erasing large sections of their scantron forms.
He was an evil genius. You had to know your stuff AND be confident in your answers.