Final Exam

Curly (of the 3 stooges fame) is   appearing for   his  University
final examination which consists of  Y/N 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
wallet out, removes a coin and starts tossing the coin and marking the
answer sheet - Y for Heads and N 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  desperatley throwing the coin, swearing
and sweating.
The invigilator, alarmed, approaches him and asks what is going
on.
"Oh, I finished the exam in half an hour." he says,
"Now I am rechecking my answers."