All apparel and footwear:
At the main menu, hold L + Y and press Right, Right, Left, Up, Up, Up, Down, Left.
Mini-players:
Pause the game, then hold L + Y and press Up, Left, Down, Down, Right, Down, Up, Left.
Normal Players:
Pause the game, then hold L + Y and press Right, Right, Up, Down, Down, Left, Right, Left.