Multiple choice

Last semester I took macroeconomics and didn't have a clue what I was doing (as cited on the final exam). There were 80 multiple choice questions. For some reason I decided to play the game of probability and choose the letter "A" for everything. In that game, the only thing probable was that I failed.
The following day, the professor asked to see me after class. "Is everything okay?" "Sure," I said, "why? "Well, here's your test," he said and handed me a piece of paper that was covered with red ink. "Can you explain why you chose an 'A' for everything?" Knowing that there was nothing I could do at this point, I said, "Well, I've always wanted to be an 'A' student."