After finishing the game's end credits, on the "THE END" screen, press R2/L1/R2/R2/Up/X/Right/Circle/Down/Triangle/L2/R1/R2/L1/Square/Square. A menu selection noise should play if this code is entered successfully, upon which you should press Start to be taken to a secret Blackjack minigame. You start with a balance of 1000, and can only bet wagers divisible by 10. If you go bankrupt, you will be sent back to the "THE END" screen, but you can play again by re-entering the code and pressing Start.