There is a secret song in Guitar Hero that can only be accessed via a Gameshark/Codebreaker. The title of said song is "*Trippolette," by "Andrew Buch," and it contains the hardest passage in the entire game (however, the song's short length makes it beatable). The code itself replaces the song "Guitar Hero" with the secret song while it is activated (in the setlist screen, and shop).
The code is on the long side (33 lines) and is as follows:
Use a rubberband (and 3 pennies if it's really big) to hold down the green fret button. It'll make it slightly easier to play hard. This way you can have you fingers on red, yellow, blue, and orange and just strum the bar if its green. I think you'll understand how to play chords.
Go to the options screen and watch all the credits (i was bored enough to count that it will play "Guitar Hero" 4 times before the easter egg happens). After it shows the producers, video credits, song credits, etc. there will be 4 or 5 somewhat funny sentences.
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