Enter the following button presses from anywhere in the game:

Animation Gender Swap: L3, R3, L3, R3, DOWN, DOWN, UP, UP, DOWN, SQUARE
Small Head: DOWN, DOWN, UP, UP, LEFT, RIGHT, DOWN, UP, CIRCLE, SQUARE
Big Head: UP, DOWN, UP, DOWN, RIGHT, RIGHT, LEFT, LEFT, CIRCLE, SQUARE
Big Eyes: UP, UP, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, CIRCLE, SQUARE
Glass Character: RIGHT, LEFT, RIGHT, LEFT, UP, UP, DOWN, DOWN, CIRCLE, SQUARE
Oilslick Character: LEFT, RIGHT, LEFT, RIGHT, DOWN, DOWN, UP, UP, CIRCLE, SQUARE
T2 Character: L3, R3, RIGHT, L3, UP, UP, LEFT, UP, SQUARE, CIRCLE
Wraith Character: R3, L3, L3, R3, SQUARE, CIRCLE, RIGHT, RIGHT, L3, L3
Banana Mic: R3, R3, L3, L3, DOWN, DOWN, RIGHT, LEFT, CIRCLE, UP
Toothbrush Mic: R3, R3, L3, L3, DOWN, DOWN, CIRCLE, SQUARE, CIRCLE, SQUARE
Tough Crowd Audio Cheat: R3, R3, R3, R3, UP, LEFT, RIGHT, DOWN, CIRCLE, CIRCLE