In an academic setting, a misunderstanding or mistake so critical that it will cause you to fail a test. Something so bad that if you told someone about it, they would say, "dude, you are so screwed for that final. YOU SHALL NOT PASS."
Actually no, our exam isn't next week, it starts in 15 minutes... you've got yourself a Gandalf Problem right there.
by betterbeAWESOME December 5, 2011