Turn on second controller (if you have one) sign in as guest. Boom away you go. Same input goes if on PS2.

Code	Effect
L1, L1, R1, L1, L1, L1, R1, R1	All Clothes (Game slows down until another button is pressed)
hold L1 and press UP, LEFT, DOWN, DOWN, TRIANGLE, SQUARE, X, X	All gym grapple moves (not shown in stats)
hold L1 and press UP, LEFT, DOWN, RIGHT, TRIANGLE, SQUARE, X, CIRCLE	All Hobo fighting moves (not shown in stats)
hold L1 and press R2, R2, R2	Full Health (not kissing level)
hold L1 and press UP, UP, UP, UP	Have All Weapons
hold L1 and press UP, DOWN, UP, DOWN	Infinite Ammo Toggle
hold L1 and press TRIANGLE, SQUARE, CIRCLE, X	Massive Money Gain
hold L1 and press UP, UP	Refill Ammo to Max Capacity