This glitch requires the use of a turbo controller.
This can only be done before getting the grappling hook. Take a turbo controller and walk off of a ledge. Right as you walk off, push up and hold the turbo button for attack. You will slowly float down. Now do this at the edge of a bottomless pit. You will float into the pit, but will return at the top of the screen. You will still die if part of you is above the screen when you release the buttons.
Submitted by: Shadotterdan