Ninja star mode
At the stage selection screen, hold R1 R2 and select a stage to play the current level in ninja star mode. In ninja star mode, the button icons are replaced with ninja stars, which are wild cards.
Skip to song
At the stage selection screen, hold L1 L2 and select a stage to skip straight to the song.
Get Unlimited Lives
After pausing the game HOLD L1 then press X, Square, Triangle, Circle
Control time of day
The game places Parappa's neightborhood at the same time of day indicated by the PlayStation2's time setting. For example, if you set the Playstation2's time to 11:30 a.m., it will be bright and sunny in the game. If it is 7:00 p.m., it would be sunset. If you set the time to 10:30 p.m. it will be dark outside.
Get Dog House
Use the yellow hat and beat each level to get the dog house where you can listen to new music
Get Blue Hat
Finish the game 1 time
Get Pink Hat
Finish the game while wearing the Blue Hat
Get Yellow Hat
Finish the game while wearing the Pink Hat