Change Nick Kang's Cloths
While creating a license plate, enter any code bellow, then highlight Ok icon, and press L1 + R1 + X.

Code - Effect
HAWG - Become a biker
JASS - Become S & M Donkey
PHAM - Become a asian butcher
M1K3 - Become a commando
BRUZ - Become a famous boxer
B00B - Become a female punk
TFAN - Become a gangster
TATS - Become a asain lady with full body tatoos
MNKY - Become a male punk
J1MM - Become a nasty corpse
P1MP - Become a pimp
FATT - Become a police officer George
5WAT - Become a S.W.A.T. team member
B00Z - Become a street bum
HARA - Become a asian kung fu guy
MRFU - Become a asian gambling guy
FUZZ - Become police officer Johnson
B1G1 - Become your female boss
ROSA - Become your partner Rosa
HURT_M3 - Become your partner Rosa in ligneire

In-Game Cheats
During Gameplay, Pause the game, and enter the Map screen. Enter these cheat codes to enable them.

Get all moves, cars, and weapon parts
Enter: UP, RIGHT, DOWN, LEFT, UP, X

Get all melee combat skills 
Enter: UP, DOWN, UP, DOWN, X

Get all driving skills 
Enter: LEFT, RIGHT, LEFT, RIGHT, X

Get all gun skills 
Enter: RIGHT, LEFT, RIGHT, LEFT, X

Increase car size (must be inside a car first) 
Enter: DOWN, DOWN, DOWN, X

Display Nick's position 
Enter: X, CIRCLE, SQUARE, TRIANGLE 

Play Snoop Doggs Missions
During Gameplay, Pause the game, and enter the Map Screen. Enter the code to enable Snoops Missions.
R1 ,L1, up, right, left, down, L3, R3, x, Square, circle, triangle
Now save the game, and load the same profile. On the select the Episode/Mission screen, Snoop Doggs missions should be available. (You must complete the default Nick Kang missions to unlock Snoops missions).