Start a new game and pause the game. From the pause screen choose the cheats option. Once entered correctly they will be listed on the cheats screen.

Cheat Effect
NOPAINNOCANE God Mode
COOLLEVELCHEATCODE Level Select
YESTERDAYYOURZEBRADIE Clear Map
ANYANDALLCODE Unlock Doors
CANEREADYTOROCK Restore Health
FISHININABARREL Unlimited Ammo
CHARLIEHUSTLEOVERDRESSEDROMEO All Weapons
FRIENDLIESTGODINGALAXY Level Up Weapons
DEADREDPARTYSHOES Big Feet
BUTTCHEATCANSURPRISE Big Head
CHARLIEOSCARLIMADELTA Enemies Thawed Or Frozen
CHARLIEALPHANOVEMERECHO Change Time Factor