It seems like the real character here is Graham, who I've never met, but I do have a story about his collaborator Bruce Rothschild, who was my professor for junior-level linear algebra.
In those days, you either gave your professors little self-addressed stamped postcards to tell you your grade, or went to their offices to ask them. I took the latter approach with Rothschild. "What grade were you expecting?", he replied. I confessed that I thought I would probably get an A. "You're getting an F", he said. "I'm giving everybody the opposite of what they expect."