We were the Death Eater Quidditch squad - I was Peter, number 0 (of course). To explain my weird expressions and posture during our (awesome) entrance, I found myself roleplaying Peter - freaked out, eyes darting side to side, pulling his cloak tight around him to hide the red lining inside, etc. We met up Friday night o make our shirts, and ended up becoming fast friends.
Our opponents were the Invaders, who had their own awesome shirts made before they even arrived and who were tough opponents - but not tough enough to beat us. ;) They were all super cool, and it was a privilege to play against them.