Maybe it's not a real code. These are the real ones. If it's not one of these, it's a fake.
Costume - C,B,A,A,C,A,B,C.
Hair Potion a.k.a. Hair Gel - A,C,B,C,A,B,A,C.
Love Potion a.k.a. Honey - B,C,B,A,C,A,B,A.
Steak - B,A,C,B,C,A,C,B.
Whole Cake - A,B,B,A,C,B,C,C.
Special Mimitchi Costume...