When you're at the main menu, Press Left, Up, Left(2), B, Up, Left(2), B, Y, Down, Up, B. This little mini game requires you to bounce fishes across a toxic pond. High scores are under your XBL GamerTage.

At the main menu, enter Left, Up, Left(2), B, Up, Left(2), B, Y, Down, Up, B. Use the Left Analog-stick to for directional entries. You can't save the game with this code. And you won't be able to play the stages unless you complete the game (only for the XBL version).