Go to the options menu and select "Cheat". Now, you have to combine the columns of words to form one of the following codes. Then, pause the game, then enable the cheat from the menu.
God mode: TRIASSASSINDONTDIE
Restore health: LAMEYANKEEDONTFEED
Fill Bloodlust: ANGRYXXXINSANEHOOKER
Time Factor mode: NAKEDNASTYDISHWASHERDANCE
Level Select: ONTHELEVEL
Enemy Freeze: DONTFARTONOSCAR
Show Weapons: SHOWMEMYWEAPONS
Gratuitous Dismemberment mode: INSANEGIBSMODEGOOD
Juggy mode: JUGGYDANCESQUAD