Press  Enter  to  bring  up the communication window and type the
codes below:

Code                    Result 
teamgod                 Team God Mode 
avatargod               God Mode 
stumpy                  No Limbs Mode 
nobrainer               Dumb Terrorists 
explore                 Can't Win 
5fingerdiscount         Reload All Items 
bignoggin               Big Head Mode 
meganoggin              Mega Head Mode 
clodhopper              Clodhopper Mode 
1-900                   Heavy Breathing 
turnpunchkick           Side Scroller(2D) Mode 
theshadowknows          Invisible Mode 
teamshadow              Team Invisible Mode 
wounddeath              Unknown 
silentbutdeadly         Fart Mode 
fastactionresponseteam  Unknown 
monocle                 Monocle Mode 

In-Game Codes:
F7 = Unlocks turbo mode
F8 = Turns off turbo mode
F10 = Enters Debug mode 

Debug Keys:
A = AI on/off
M = Freezes you
F6 = Become other people
F9 = Back to yourself
F10 = Exit Debug Mode
F12 = Level Skip
F7 = Kills you