At the Character Select screen, press Del, then enter any of the following "Codes": Code Effect.
itsgallus - All Levels, All Cities
iamthelaw - No Police itcouldbeyou - Gives You 999999999 Points suckmyrocket - All Weapons, Armor, Get Out of Jail Free Card itstantrum - Unlimited Lives hate machine - Raises Point Values buckfast - Press the asterisk(*) on the Numpad and get all weapons porkcharsui - Diagnostic Mode iamgarypenn - Extra Offensive Language Mode iamnotgarypenn - Disable Code Above hate machine - 10x Multiplier Bonus porkcharsui - Game Diagnostics heartofgold - View FMV Sequences enigma - UFO Police Cars (first enter any of the above)