Use any cheat to earn this achievement, just type the cheat whilst in game and boom, achievement is yours. Please note that the cheats will potentially cause issues with other achievements. (the cumulative ones may stop counting)
*** Spoiler - click to reveal ***DNCORNHOLIO - Toggles God mode on/off
DNKROZ - Toggles God mode on/off and toggles infinite Jetpack
DNSTUFF - Gives all weapons, all inventory items and all keys
DNITEMS - Gives full armor, all inventory items and all keys
DNINVENTORY - Gives all inventory items
DNWEAPONS - Gives all weapons
DNKEYS - Gives all keys
DNHYPER - Gives Steroids
DNSCOTTY#** - Warps to a level
(Replace # with the episode number and the two * with
the level number, e.g. DNSCOTTY203 takes you to Episode 2, level 3)
DNMONSTERS - Toggles monsters on/off
DNCASHMAN - When the Open button is pressed, money is thrown out (Duke is damn rich!)
DNVIEW - Same as pressing F7
DNRATE - Shows the Frames Per Second (FPS)
DNDEBUG - Shows some debugging information
DNSKILL# - Changes the skill level to whatever you input for # (enter 0 for no monsters)
DNBETA - Displays the message "Pirates Suck!"
DNTODD - Displays the message "Register Cosmo"
DNALLEN - Displays the message "Buy Major Stryker"
DNCOORDS - Displays your coordinates
DNSHOWMAP - Displays the entire map
DNCLIP - Toggles Clipping Mode
(If you walk into empty space, such as inside walls, you die.)
(In versions 1.4/1.5, walking into empty space will not kill you.)
DNUNLOCK - Unlocks all doors and opens those that are not locked
Cheats sourced from http://dukenukem.wikia.com/wiki/Cheat_codes