I'm a high school teacher and can confirm that what you saw happens quite often out here in SoCal. With the whole "Ultimate Fighter" and UFC craze taking place kids are really enthralled by the fight scene. So what they do is they find a quiet place, or a friends house with a nice backyard, and stage their own fights. I've had kids try to show me their fights they saved on their camera phones. Funny thing is many of these kids are also the biggest "tough guys" on campus and even try to intimidate teachers. Well once they learn that I've been training Brazilian Jiu-Jitsu myself for about eight years and have trained with guys who actually fight in bigger venues, they sort of tone down the tough guy image and actually focus on learning in my class.