Someone that's into "extreme" sports such as down hill mtn. biking, BMX, motocross or anything that you can get "rad" with. A flat brimmer will wear a ball cap with a flat brim with Oakley sunglasses and can usually be seen drinking a Monster Energy drink. A flat brimmer will think he or she is better than the rest and loves to pose for photographs.
Did you see that flat brimmer with the Fox jersey acting like a douche to those other riders?
A small private school that has it's focus on attempting to be a sports school or a theater/arts school, yet managing to be neither at the same time. It's a place where the rich spoiled K-12 graders go to school for the sole purpose of excluding those who do not wear designer clothes, play sports, or own an iPhone.