How to do the animation glitch:
Stand next to a car, Open the Menu "Select". Go on "Action" and choose the one you want by pressing "A" (or X on PS3) and soon after press "Y" (or triangle on PS3) to get in the car.. Then spam "A" (or X on PS3) to freeze the animation while you're getting into the car. :) Might take a couple tries. One thing that sucks about the glitch is that when you die after doing it, you won't be able to do it again until you either leave the game and come back, or go to the xbox live store (where you buy the shark cards) and come back into the game.