Extreme-G
N64

Enter these codes as the player's name (press R at the Bike Selection screen). 
If done correctly you will hear a sound: 
fergusFace on cycle
rollerEveryone is a rock
xtremeFast turbo
antigravUpside down tracks
magnifyMagnifies
stealthYour bike is invisible
fisheyeFisheye lens
ghostlyTransparent track
wiredWire frame version
uglymodeSilly graphics
arsenalWeapons when you need 'em
bananaSuper-slippery tracks
nitroidInfinite turbos
Xgteam Face will be on your car (go back and enter a designers name ash, shawn). 
At the Password screen, enter:
81GGD5 for access to all the bikes and tracks

61DDB5 for only the cars Neon and Roach
Thanks to Revolution readers Killerkid0, Blarkin007, Mitch Olsen, and Maximilien

 DeLIBERA!