Pause game play, then press Left(2), Right(2),
Circle, Square. If done correctly the
phrase "Nuke Em" and a voice will confirm correct
At the main menu, hold Square + L1 + R1 and press Up, Down, Left, Right. If you entered the code correctly, you will hear a sound.
All Weapons with Infinite Ammunition
Pause the game and press Square, Circle, R1, L1. If you entered the code correctly, you will hear a sound.