Level select 
At the first options screen, where Abe says "Hello", hold R1 
and press Down, Right, Left, Right, Square, Circle, Square, 
Triangle, Circle, Square, Right, Left.

View FMV sequences 
At the first options screen, where Abe says "Hello", hold R1 
and press Up, Left, Right, Square, Circle, Triangle, Square, 
Right, Left, Up, Right.

Invincibility 
While playing a game, hold R1 and press Circle, Triangle, 
Square, X, Down(3), Circle, Triangle, Square, X. 

Instant voice puzzle solution 
While playing a game, hold R1 and press Triangle, Up, Circle, 
Left, X, Down, Square, Right. Then, select any sound to solve 
the game's voice puzzles.

Green air mines 
While playing a game, hold R1 and press Up, Left, Right, Square, 
Circle, X. Then, Abe will produce a green air mine every time he farts.