You may already know that it's possible to stomp a Koopa Paratroopa twice in mid-air. If your second stomp occurs when the Koopa Troopa is 1 or 2 blocks above the bottom of the screen, his shell will be floating in mid-air! Of course, the only way to get the Koopa Troopa 1 or 2 blocks from the bottom would be to stomp on him over a pit. For a real challenge, try to double-stomp a Paratroopa and land on solid ground. When the Koopa Troopa pops back out of his shell, he'll start walking in mid-air! It's not the easiest glitch to pull off, but a good place to practice is World 4-3.