Get a Ghost stuck on the Scarab

On the level Metropolis, when the doors open and Perez (a Marine) comes out, grab a Ghost and drive it up the stairs. Wait for the Scarab to pass and go all the way up to where the Scarab stops. Knock the boxes off the edge and clear the deck of the Scarab. Back all the way up to the wall and boost onto the Scarab. If you did it right you should be on. Now carefully drive up to the top of the Scarab. You should get to a point where you can't move, even if you boost. It does as much good as a turret. If you get off, the Ghost will turn until it is facing forward and will still hover, but without the light that normally comes with it.