When you are called on by the teacher and you should the answer out loud and proud...
BUT IT'S WRONG!!!

https://youtu.be/iPZWowkL8HM

When your class gets a graded test back and you think you did better than your friend and confidently tell her, but she shows you her MUCH BETTER grade.
When you forgot you have a test in a class, and you totally FLUNK IT!!!!!

(Me when I flunk a test)
When you get a bad grade and you crush sees it!!!!!!!!!!!!!!!!