This is just a fun little glitch on the ferry boat online level. When you start from i think red's side, you will need to go up the stairs and to the top of the boat, there will be around the corner a small set of stairs with 3 doors, two down below across from each other and one on your level. You will be on top of the stairs and crouch down. Use your primary weapon to zoom in on the dark blue strip on the roof across from you(near 3rd light)then just hold forward on joystick and walk forward crouched as fast as you can. It may take a few tries but it is for fun and won't affect gameplay much.