Zelda: Link's Awakening Easter Egg - Play as Dark Link

NOTE: You MUST be using an emulator and NOT be playing the DX version of this game.

First off, make sure you have the sword. Now, equip your shield button with anything other than the shield itself. Here is where the tricky part begins; walk in quick circles, while holding DOWN on the directional pad (the reason why you can't use an actual Gameboy). Keep doing this until you see an L-2 shield in your hand, and quickly hold the sword button, as if charging a Spin Attack. Note the fact that you look like a really dumb shovel. Release. You will do a Spin Attack and you will look like Dark Link.
ANOTHER NOTE:This glitch/egg/thing will reset if you enter/exit a building or cave, so if you want to beat the game as Dark Link, you should get good at doing the glitch.