Halo 2 Easter Egg - Metal "Baloons"

on the level Outskirts, after you kill the hunters, in certain ares there are these metal tubes that you can knock down or move around that are about as tall as you are, anyway, some of them have a knob on the top of them. knock it down and shoot it with a battle rifle or one of the sniper rifles and it will fly of like when you let the air out of a balloon!