Santa's Final Exam...

Santa reported for his university final examination, which consists of "Yes/No" type questions. He takes his seat in the examination hall, stares at the question paper for five minutes , and then in a fit of inspiration takes his purse out, removes a coin and starts tossing it, marking the answer sheet yes for heads and no for tails .
Within half an hour he is all done whereas the rest of the class is sweating it out. During the last few minutes, he is seen desperately flipping the coin , muttering and sweating.
The moderator, alarmed, approaches his and asks what is going on?
Santa replies, "I'm rechecking my answers and I don't think I did very good