Listen to ACID LINE: 

When you go into the Options area of the main screen,
go to Sound Options. You can listen to most of the 
songs from the game in the Music Test. To listen to 
Robo-Z Gold's song, "ACID LINE" you have to hold left
or right on the selector and it should cycle through
the songs real fast. While it cycles you should 
notice "ACID LINE" apear before "The Heat is on" when
scrolling right. The key is to stop it on the song 
and then select it, a good tactic is to go 3 songs 
over in one direction and try it from there.