At the "start game" screen, choose the following icons and enter the corresponding codes:
Two-player boss games -- choose Big Red icon, enter "*JC" as a code.
All minigames -- chose Daffy Duck icon, enter "?BN" as a code.
Level select -- chose Marvin Martian icon, enter "#OP" as a code.
No whack in boxes -- chose Taz icon, enter "!WB" as a code.
All gallery images -- chose Tweety icon, enter ".RT" as a code.