This is a pretty straight forward thing to get. when going to Nazi zombies and you are sitting in that chair look down at your arms and tap bolth bumpers repeatedly to get out of the chair once you are out of the chair. now walk around the room untill you find the computer press X and then you can type DOA in the computer, you unlock a zombie mode called dead ops arcade. In this mode, you can play a remake of a an old game called smash tv. You can use a thing called a speed boost and when you use it you boost foward and destroy everything in your path. On the 1st or 2nd round, get a crowd of zombies  and simply boost through them*you must kill 20 of them*

as i said, it is a simply trophy.