The Simpsons: Hit And Run cheats and cheat codes for Gamecube

Go to the options screen and enter the following cheats:
Note: If teh codes are accepted, you should hear a sound of horn.

Red brick car: Hold L + R and press B, B, Y, X.
Invincibility: Hold L + R and press Y, A, Y, A.
Bigger jumps: Hold L + R and press X, X, X, Y.
Show speedometer: Hold L + R and press Y, Y, B, X.
Grid view: Hold L + R and press B, A, B, Y. 
Change views: Hold L + R and press B, B, B, A. 
Psychedelic view: Hold L + R and press Y, B, Y, B.
Different credits audio: Hold L + R and press A, X, X, Y.
Blow up vehicles: Hold L + R and press Y, Y, X, X.
Faster cars: Hold L + R and press X, X, X, X.
Turbo cars: Hold L + R and press Y, Y, Y, Y.

Unlock all bonus cars: Hold L + R and press A, B, A, B.
Note: You need complete 100% of the game. Resume the finished game 
and find a telephone. Hit R or L at the car selection screen.

Drive wrecked car:
Jump out of your car as it blows up, then go back to the wreck and hit Y. 

Halloween theme
Modify the system date to October 31st

Thanksgiving theme
Modify the system date to the last thursday in November

New Year's theme
Modify the system date to January 1st

Christmas theme
Modify the system date to December 25th