Tony Hawk's Underground cheats and cheat codes for Gamecube

Select "Cheat Codes" at the options menu, after enter the following codes:

All movies: Enter "digivid"
Moon Gravity: Enter "getitup"
Play as T.H.U.D.: Enter "NOOO!!"
Perfect rail balance: Enter "letitslide"
Perfect manual balance: Enter "keepitsteady"
Perfect skitches: Enter "rearrider"

Untested cheats:
Unlock all levels: Enter "Road Trip"
Master code: Enter "havethemall"
Another Master code: Enter "fillitup"
THUG Music code: Enter "HOLESHOT"
Every Skater: Enter "getemall"
Perfect skitches: Enter: "rearrider"

Unlockable cheats: 
Complete 129 of 129 Goals to unlock th following cheats:
Always Special
Cool Specials
Flame Grinds
Kid Mode Get
Moon Gravity
Perfect Manual
Perfect Rail
Perfect Skitch
Rollerskates

Unlockable movies:
Always Hard: Find all 9 Secret Tapes. 
Bails 1: Find 3 Secret Tapes 
Bails 2: Find 6 Secret Tapes 

Unlockable characters:
Gene Simmons: Finish the game on normal mode. 
Iron Man: Finish the game on beginner mode. 
Pedestrians: Perform every gap. 
T.H.U.D.: Finish the game on sick mode. 

Alternate Ending 
Finish the game twice on any difficulty. 

Create-a-deck mode 
Win Slamma Jamma in Story Mode 

Cars:
Beat up Old Sedan: Finish mission "Pineapple Killer" in Hawaii 
Limo: Finish mission "Pick everyone up in the Limo" in Vancouver 
Old Sedan: Finish mission "Nut Vendors Unite!" in New York 
Police Car: Finish mission "Revenge!!!" in Tampa 
Russian Sedan: Finish mission "Party Favors" in Moscow 
Security Cart: Finish mission "No one likes a dude festival" in San Diego 
Street Warriors Race Car: Finish mission "Get in tight with the Street Warriors" 
in New Jersey 

Leafblower: Do either mission: "Race the blowcart" or "Ralphie got busted" 
in Vancouver 

Pre-made skaters
Go to create a skater and enter any of the following names:

ZiG
Yawgurt
Y2KJ
woodchuck
TSUEnami!
TOPBLOKE
Todd Wahoske
THEDOC
The Swink
The Kraken
tao zheng
Steal2Liv
Stacey D
Skillzombie
sik¦
POOPER
NSJEFF
Noly
M'YAK
moreuberthaned
Mike Ward
MARCOS XK8R
leedsleedsleeds
Johnny Ow
Joel Jewett
Jeremy Andersen
Jason Uyeda
Henry Ji
Hammer
Guilt Ladle
grjost
Greenie
GMIAB
Glycerin
GEIGER
FROGHAM
fatass
deadendroad
DDT 
Dave Stohl
Dan Nelson
Daddy Mac
crom
CodePirate
ChrisP
Chris Rausch
Chauwa Steel
Big Tex
Bailey
arrr
Andy Marchel
Alex Garcia
Alan Flores buffoon
Akira2s
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