From the main menu, go to “Options”, then “Cheats”, then “Enter Cheat”. Then play the following notes, you must strum every note/chord.
(G=Green, R=Red, Y=Yellow, B=Blue, O=Orange)

Code
Effect

(BY) (GY) (GY) (RB) (RB) (RY) (RY) (BY) (GY) (GY) (RB) (RB) (RY) (RY) (GY) (GY) (RY) (RY)
Air Guitar

(GR) (GY) (YB) (RB) (BO) (YO) (RY) (RB)
Easy Expert [...]