If you are talking about the V3 costumes it is the characters nyatchi and hohotchi.You get thes costumes by entering the passwords into the shop.
1. ABBA ACBA = cake
2. BCAB ACBC = steak
3. CBAC CABC = cuckoo clock
4. AABB CACB = RC Car 2
5. CACA BABC = Nyatchi Costume*****
6. ACBB BACC = hair gel
7. BCBC CABA = love potion (honey)
To get the hohotchi costume you must enter all the codes but the last code you enter wont be the item.It will be the hohotchi costume.