When you turn on your Gameboy/Colour or DS/Lite make sure the game is Spyro Fusion, then when it says GameBoy and a sparkle goes past it, hold down the two shoulder buttons, Im not sure if it works on a Gameboy since I did this on a DS ^^.

Then some credits load up in the classic Crash Font and Orangey Red colour, then you choose the language and then you see Crash Bandicoot in the top right corner stepping his foot in rythm with the background music, and you have to press the appropriate button that show up when they come into the green circle by Crash.