To do the Zanzibar Warthog trick, go to the Halo 2 multiplayer map Zanzibar and choose Dreadnaut, a variant of Juggernaut. Drive both Warthogs and both Ghosts to the big wheel in the middle. Drive 1 Warthog into the wheel, get out, jump into the other one, and push the first Warthog so the passenger seat is in line with the spokes of the wheel. If done correctly, the Warthog will fall on top of the inner wheel, making a great sniping spot. This can also be done with Ghosts in the same game variant!