Unlimited supplies:
Press Back, R, L, Back, click Right Analog-stick, press L at the "Extra" menu.
Unlimited health:
Press Left, Right, Up, Down, click Left Analog-stick, X at the "Extra" menu.

Hippy blood:
Press White, Right, B, Down, R, Back at the "Extra" menu.

Extreme ragdoll:
Press Up, Up, Up, Black, Black, Black, Up at the "Extra" menu.

Low gravity ragdoll:
Press X, X, X, B, B, B, Up, Down at the "Extra" menu.