First use this one (Hit BACKSPACE and type):

!throw me a frickin bone here - Enable cheats

You may now hit backspace and type any of the other codes:

Code Effect

!captain scarlet - God Mode
!full monty - God Mode Plus Items
!stay frosty - Give Sarge a ForceField
!henry - Gives 30 Insecticide Spray
!harsh language - Gives 20 Fly Swatters
!here's a lockpick... - Give Unlimited Flame Napalm
!mib - Give Sarge a Laser Rifle
!this one goes to eleven - Gives 3 Napalm Strikes
!scotty - Give 3 SpaceMen Renforcements
!hey stifler - Give Unlimited Glue
!one time... - Give 3 Baseballs
!spiny norman - Give 3 HammerMines
!let me down - Drops Sarges Health to almost 0
!pump me up - Give Sarge a Steriods Boost
!rate me - Show FPS
!roody-pooh - Give Unlimited Air Attacks
!the meek - Lose Scenario
!cut to the chase - Win Scenario
!halloween - Changes the Enemy Troops Into Zombies
!time for bed - Lose Scenario
!mona lisa - Gives Random Item
!florence - Gives Unlimited MediKit
!johnny ricco - Gives 3 Paratroopers
!peep show Gives - 3 Recons
!heavenly glory - Gives 3 AirStrikes
!yippee!!! - Gives A Sniper Rifle
!penny - Gives Unlimited M80's
!hey dante - Unlimited Aerosol
!the sun - Unlimited Magnifying Glass
!whistle and flute - Give Sarge a Flak-Jacket
!i woke up this morning - Gives 9 Blue Disguise
!no sunblock - Gives 9 Tan Disguise
!incognito - Gives 9 Grey Disguise
!i got two words for ya... - Gives A MineSweeper
!haunt haunt haunt! - Gives 10 Explosives
!sprinkles - Gives 30 Mines
!i like to keep this handy - Gives Unlimited Bazooka
!patty melt - Gives Unlimited FlameThrower
!you want some - Gives Unlimited Grenades
!disco inferno - Sets Sarge on fire (But Doesnt Hurt Him)
!disco is dead - Extinguishes Sarge's Fire
!no one expects - Summons a Horde Of Enemy Troops
!italian job - Sets Off A Huge Explosion Around Your Sarge
!its dark - Hides All Enemy Troops on Mini-Map
!door - Teleports Sarge to Cursor Location
!only human - Unknown Effect
!sarge calibur - Unknown Effect
!know your role... - Unknown Effect
!hello neo - Unknown Effect
!vic fontaine - Unknown Effect
!mojo - makes enemys move again
!game over - Unknown Effect
!when all else fails... - Unknown Effect

Update Cheat Mode:

After activating cheat mode, type

Code Result

!there is no spoon - and you can see every thing on the mini map.
!oh behave - will freeze the enemys and !mojo will make them move again.