you have to use this code: gr-gr-ry-yb-bo-o-o-o-b-y-r-g-r-g-yb-ry-gyo-gyb-ryo-ro-gy-grb-gry-gr-gr-g-go-gr-gy-gyo-b-gy-gy-gr-gr-

YO, RB, RO, GB, RY, YO, RY, RB, GY, GY, YB, YB, YO, YO, YB, Y, R, RY, R, Y, O

idk gy khbb your gsyyyyyy r

If you finish the career mode you should have some sort of note come up after this guitar battle which will tell you some sort of unlockable - cheat button sequence. Otherwise you to go options -> cheats -> enter -> (GR) (B) (GR) (GY) (B) (GY) (RY) (O) (RY) (GY) (Y) (GY) (GR) - G being green, R being red, etc. You have to hold that fret down and strum, 2 frets in an enclosed bracket means 2 frets at once. Hope this helped!

There are 2 syllables. Din-gy.