Mii
From Nookipedia, the Animal Crossing wiki
A Mii is a digital avatar which can be created on a Wii. It is created using the Mii Channel on the Wii, and can be used as the player in multiple Wii games, most notably in Wii Sports, to represent the player, and the Miis can also be moved from system to system by downloading then, or by saving them on the Wii Remote and placing a copy on another Wii. In Animal Crossing: City Folk, in addition to modifing your basic face, the player can go to The Shampoodle Salon and can buy a mask in the shape of a Mii's face. On the first time you do this, it will be free.
