Overload glitch (Halo 2)
From Halopedia, the Halo wiki
First, go to an object that is not part of the environment, but part of the scenery (bridge on Zanzibar, floating platform on Midship etc.) and get seven or more people to stand on it. Put as many vehicles on the object as well. Then have the people look down. The object will eventually overload and disappear.