Make it to the 20th stage without dying and instead of a ribbon or sneakers you'll see a special gate. Enter it and receive 10000 point diamonds.
On the start screen press: Down, up, down, up, right, down, left, down, up, down. A message will appear to signfy that the code has been entered correctly. When the message has come up, start a game as normal then, during play, press the following buttons:
R1: Skip to next level
L1: Return to previous level
R2: Bring up an options menu
L2: Confirm selections on the options menu