Accomplish the following tasks in Challenge Mode and then go to the options to pick the cheat unlocked:
Get all cars: hit 11 Bonus Stunt items during Challenge 8
Get Infinite Ammo: hit 50 barrels during Challenge 18
Get Infinite Health: hit 180 barrels during Challenge 17
Get Infinite Turbo: collect 8 Zappers during Challenge 4
Get all items: hit 30 barrels during Challenge 7
Get all worlds: get the hidden Key during Challenge 18
Get Timer Speed: hit 60 barrels during Challenge 12
Get Upgraded Laser: win Challenge 18 on Very Hard difficulty