On the zombies map Call of the Dead, open all the doors to the lighthouse except for the door right next to the AK74u.

Walk up to the side of the short stair set to the left of the AK74u. Go to the right of the stairs and aim your crosshairs at the ground.

Center the crosshair of the far right of the stairs and slowly walk up. You should be positioned so that the left side of the crosshair is on the stairs and the right side is not.

Once you have walked as far up as you can while keeping the crosshairs centered, you can turn, aim, and shoot without zombies attacking you.

They will go through to the other door that is still closed and which you can shoot them through. Also works on George.