Mini-Players

Pause game play, then hold L1 + Triangle and press Up, Left, Down(2), Right, Down, Up, Left.

Normal size players

Pause game play, then hold L1 + Triangle and press Right(2), Up, Down(2), Left, Right, Left.

All apparel and footwear

Hold L1 + Triangle and press Right(2), Left, Up(3), Down, Left at the main menu.