Ever heard of the "cloud glitch" in Super Mario World? It's a technique that allows you to spawn a usable Lakitu cloud in your item box, which you can then use to speed through the game. Heck, the glitch even allows you to skip some of the animations in the final Bowser fight, peculiarly enough.
Here's a tutorial by A+Start on how to do the glitch discovered by Masterjun3, along with a technical breakdown of why exactly the glitch is possible. Be warned, though, it's the sort of glitch that requires precise inputs -- so it might take a few tries to master.