Highlight the "Multiplayer" in the options menu, then hold L1 + R1 + R2 + Left and press X to display the cheat menu. Then, enter one of the following codes to activate the corresponding cheat function:

5-0 Mode:
Enter "BDK" as a code at the cheat menu.

Sidecar Mode:
Enter "CMB" as a code at the cheat menu.

Jailbreak Mode:
Enter "KLFSDA" as a code at the cheat menu.

Four Nitros in Jailbreak Mode:
Enter "FDMFG" as a code at the cheat menu.

Hitch A Ride:
Position your bike behind a car and pop a wheelie. Just as you begin to jump, slam on the brake. Now you're car-surfing. Do this when a cop is chasing you. But when he ram's the car, both of you will wipe outl.

No Arrests or Crashes:
Press Start and then restart the race before getting arrested by the police or crashing.

Keep Weapons and Don't Loose:
If you have lost your weapon and you're near last place and right by the finish line, just pause the game and go to restart, then yes. When you restart, you will have another chance at 1st place an you will also still have your weapon.

The Slacker's Method:
If you are really lazy and want to win races easily just do this. After the 3-2-1 just turn around and drive in the wrong direction for a bit. KO any cops or stuff and don't get busted or wrecked. Then all you have to do is, after a while of driving the wrong way, just press START then QUIT then YES. It should say you came first. This works on random tracks so sometimes you might get wrecked. This works in Side car Co-op and possibly Solo mode

GameShark Codes

Infinite Health 
800d57665a5a 

Infinite Bike Damage  
800d577c4040  

Always Win  
800d577e016e  

Infinite Nitro  
300d81ec000a  

Stop Timer  
800d5d480000  
  
All Weapons/Superweapons  
800d81e401ff  
800d81e8ffff  
800d81eaffff  
  

Thanks to Revolution reader Brian T, Scott Handel, G-DOGG, Bill, Alex & Paul and mazza!