Any cheat code you type on your keyboard while in-game will unlock this achievement.
DNCORNHOLIO - Toggles god mode (invincibility and limitless jetpack)
DNGOD - Toggles god mode (invincibility and limitless jetpack)
DNCLIP - Toggles clipping (walk within walls; may sometimes kill you or crash game if you walk outside the map)
DNCASHMAN - Throws cash when USE button is pressed
DNMONSTERS - Toggles monsters (hides them on sight when enabled; shows again and combats on sight when disabled)
DNVIEW - Toggles view mode (same as F7)
DNWEAPONS - Gives all weapons/ammo
DNKEYS - Gives all access cards
DNINVENTORY - Gives armor and inventory items
DNITEMS - Gives armor, access cards, and inventory items
DNSTUFF - Gives everything
DNHYPER - Gives steroids and uses them
DNSCOTTY### - Warp to a different episode and level (101 = Hollywood Holocaust)
DNSKILL# - Restarts level with skill set to 0-4 (0 = no monsters, hazards and items; 3 = Come Get Some)
DNUNLOCK - Toggles all locks on level
DNSHOWMAP - Reveals the whole level in map view
DNCOORDS - Displays coordinates in map view
DNDEBUG - Displays game variables in map view
DNRATE - Displays frame rate in map view
DNALLEN - Displays message: Buy Major Stryker
DNBETA - Displays message: Pirates Suck!
DNTODD - Displays message: Register Cosmo today!