Change your costume and Shank's close-up appearance.

Costume	How to unlock
ANY-S Shank	Enter the Konami Code: Up(2), Down(2), Left, Right, Left, Right, A, B (may be different depending on your controller)
Dance Shank	Beat the game on normal.
DeathSpank Shank	Beat the game and enter this code: Up, X, Down, B, Left, Y, Right, A (may be different depending on your controller)
Horror Shank	Get 100 chainsaw kills.
Kung Fu Shank	Get 1000 kills.
Red Pajamas Shank	Get a 150-hit combo.
Shank the Gimp	Get 500 creature kills.
Spartan Shank	Complete the co-op backstory mission.
White Pajamas Shank	Get a 100-hit combo.
Wildman Shank	Beat the game on hard.