Cheerleading does seem to be a kind of uniquely American deal, pretty much confined to the big two, football and basketball, seems to have started in 1898 at the University of Minnesota by a student, Johnny Campbell. Female cheerleaders start in the 1920s, also on the college level. So it's pretty much a 20th Century American deal too. When it comes to large people in large groups doing stupid stuff, we're number one! U.S.A.U.S.A. But the Brits sing to their soccer teams, so the idea is the same, the level of formality is the only thing that changes.
And by 'be a cheerleader' do you mean getting out there and cheering my football team on to victory by using such clever tactics as chanting "We've got spirit yes we do, we've got spirit, how 'bout you?" while point to the other side taunting them into letting their team down? That kind of stuff? Always seemed stupid to me. Football is pretty distant from the crowd, even at the Pro level and on the field a lot of that is just a noise wash anyway. Basketball, yeah, that rocks. I've been in small town HS gyms, packed with people that were just at an elevated state of being while the game was on. Same too with the big college teams/games. It gets really loud at those places and the cheering becomes far more a part of the game.
So yeah, I bet being a cheerleader for K or K State in the big home game is a hoot. You do get to go to all the games, and for the big time college teams that's some nice travel perks.
Or do you mean 'be a cheerleader' in the sense that that's what I do on Friday nights, but I'm also student body president, head of the yearbook committee, homecoming/prom queen, National Merit Scholar and possibly one of the most popular girls that has ever lived?
What we need is one of the artistic types to design cheerleader outfits for the Roman Games. That would be hot.