Official X-Box Magazine Disk #38 (Xbox)
CheatingDome.com
Unlock The Easter Egg Demo!
Go to the playable demos screen. On the demo screen, hold down the left trigger and press A, Up, X, Y, Left, Right, B, B, Down, Down, Y, Left, X, Right, A, Up, Down, and release the left trigger to unlock The Incredible Easter Egg Demo.