Here are the 5 codes:
ACBCABAC = Hair potion
CBAACABC = Costume
ABBACBCC = Whole Cake
BACBCACB = Steak
BCBACABA = Love Potion
To do them, go to the shop. When you see the shopkeeper, press button A. three times until the shopkeeper looks surprised/sad. Then type in your code. You may use the codes more than once but the first time you do the codes, the items are free. After that, you have to pay for them