Different Heads
You can alter the heads within the crowd by pressing specific buttons during the title menu screen. Press "R1," "X," "R2," "X," "R2," "X" and "R1," and the entire crowd will have giant eyeballs for heads. Press "R1," "R1," "R2," "X," "R1," "R1," "R2" and "X," and the entire crowd will have monkey heads. You can change your head into a horse head by pressing "R2," "X," "X," "R2," "X," "X," "R2," "X," "X," "R2," "X," "X," "R2," "X," "X," "R2" and "X." Pressing "R1," "R1," "X," "R1," "X," "X," "R1" and "X" will give you a flaming head.
Five-Star Rating
Receiving a five-star rating for a song is the highest honor you can receive in "Guitar Hero II." You can achieve this goal with a cheat. Enter the practice mode and choose a section of a song. Play the song at your desired speed and when it finishes, quickly unplug your PS2 controller before plugging it back in. Go to the "quick play" option and play the song. Instead of needing to play the entire song, you will only have to play the section you opened in the practice mode. Master that section, and you will get a five-star rating for the entire song.
The Grim Ripper
The Grim Ripper generally plays with one type of guitar: the scythe. However, you can alter this. While in career mode, select the difficulty of game play you desire. It doesn't matter which you choose. Now, select any guitarist you want other than the Grim Ripper. After this, select the guitar of your choice. Now, go back and change your character from whomever you picked to the Grim Ripper and he will play the guitar you have chosen.
The Guitar
Some guitars can be unlocked if you beat certain aspects of the game. While these aren't necessarily cheats, they do add a twist to gameplay. Defeat the entire game on easy mode and you will unlock the fish guitar. Receive a five-star rating for every song throughout easy mode, and you will unlock the USA guitar. Defeat the game on the medium difficulty level and you will unlock the casket guitar. Receiving a five-star rating for every song throughout medium mode will unlock the Viking guitar. Defeat the game on the hard difficulty setting while receiving a five-star rating on every song and you will unlock the eyeball guitar. Beating the game on expert mode and receiving a five-star rating for every song will unlock the log guitar.