If you fail one class and don't go to summer school, what happens?

I passed all of my classes except for US history because that teacher doesn't like me. Here's proof: When I was taking the final for the class, that retard took my pen and threw it on the floor so I wouldn't finish it. So because of that, I failed the class. And I refuse to go to summer school just because the teacher doesn't like me. What would happen if I didn't go?