Frogger 2: Swampy's Revenge

Pause the gameplay, then enter the following button combinations:

Transform coins into Mad Garibs:
Hold X and press Right, Left, Right, Left, Up, Up, Left, Right.

Temporary invincibility:
Hold X and press Left, Left, Up, Left, Down, Right, Right, Right.

Unlock all characters:
Hold X and press Left, Right, Left, Left, Left, Up, Left, Left.

All extras and bonus levels available:
Hold X and press Right, Up, Up, Down, Right, Down, Right.

Infinite lives:
Hold X and press Down, Down, Up, Down, Right, Down, Up, Up.

Skip stage:
Hold X and press Right, Left, Up, Up, Up, Right, Left, Left.

Select stage:
Hold X and press Up, Down, Left, Right, Right, Right, Down, Left.