Pause game play, then select the "Audio" option at the menu. Then, press one of the following codes..

Code - Effect

R1, R1, L1, L1, Circle, Circle,, Square - Unlimited Electric Bombs
L1, L1, R1, R1, Circle, Square, Circle - 200,000 Klokkies
R1, L1, R1, L1, Circle, Circle, Square, Square, R1, Square - Refill Health