1 definition by Surlybob
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.
by Surlybob March 16, 2015