Extras menu codes 
     Enter  the  code  while  in  the  "Extras"  menu  screen. If done
correctly you will hear Bart laugh

(Note, Left/Right refers to the control pad and L/R refers 
to the shoulder buttons)

Cheat code:                                  Effect:
Triangle, Left, Right, Triangle, Square, L   Unlimited power 
                                             for all characters. 
Left, square, right, Triangle, Right, L      Unlocks all Cliches 
Square, Left, Square, Right, Triangle, R     Unlock all Movies