Go to Quick Play or Tour mode, and select "So Watcha Want" by the Beastie Boys 
on the Expert difficulty. When the song starts, put the microphone up to your 
speaker(s), and hold it there for the duration of the song. The only thing you 
will have to do is yell to activate Overdrive when it appears and tap the 
microphone for the solo parts. At the end of the song, you will have a 100% rank 
and gold stars. Note: Make sure your volume is loud enough. For just a gold 
star, select "Give It Away" by the Red Hot Chili Peppers, and do the same thing. 
You will get a 99% rank without singing. If you want a 100% rank on that song, 
you must be able to hit the last phrase in the song.