Confident!

A professor stood before his class of 20 senior organic biology
students, about to hand out the final exam.
"I want to say that it's been a pleasure teaching you this
semester. I know you've all worked extremely hard, and many of
you are off to medical school after the summer. So that none of
you gets your GPA messed up because you might have been
celebrating a bit too much this week, anyone who would like to
opt out of the final exam today will receive a 'B' for the course."
There was much rejoicing amongst the class as students got up,
passed by the professor to thank him, and signed off on his offer.
As the last taker left the room, the professor looked out over the
handful of remaining students and asked, "Anyone else? This is your last chance."
One more student rose and took the offer.
The professor closed the door and took attendance of those students remaining. "I'm glad to see you believe in yourselves," he said.
"Each of you gets an 'A.'"