An interjection said when someone makes an incorrect point and you prove them wrong on the spot, or when you beat somebody who was so full of themselves they were sure they were gonna beat you.
A: I know you were crying earlier! You were holding a tissue to your face! I'm not stupid!
B: Actually, I have a cold. I was blowing my nose. You are stupid. What now burn!
C: I'm going to crush you in football today.
D: We won. By twenty points. What now burn!