Enter the following during play. You'll hear the word "Cheater" to confirm. 

burgergod       Invincibility
moreclang       Level skip
ivegotit        All weapons, energy, and shields
treesquid       Reveal map
tuberacer       Damaged
byebyemonkey    Chase view
shananigans     Weird textures
framelength     Show framerate
deadofnight     Destroy all bots
testicus        Enable cloak    
teletubbies     Teletubby sun!