You need a Jet Trooper for the trick. Go to the bridge (the place you spawn) and find a light above without blue on it. Jetpack through the light, find a gray hallway and land.

Go to the room with those revolving pole objects. Go through the door that faces the front of the ship. Go to the poles on the right. From right to left, strafe very slowly into the space between the first and second pole. You will begin to shake. The game will randomly put you through the floor, rapidly drain all your life, or force you to fall so far through that you will be completely under the floor (allowing you to walk around random places).