Cheat mode

Pause game play, then hold L2 and press Down, Up, Square, 
Triangle(2), Circle, Down, Up, Square, Triangle. 

Extended cheat mode

Pause game play, then hold L2 and press Triangle, Circle, 
Triangle, Circle(2), Triangle, Left, Circle, Up, Down, Right, 
Circle, Left(2), Triangle, Right, Circle, Left(2), Triangle, 
Circle, Down, Circle(2), Right.