The Windup Sir Nibbles is a toy introduced in Nintendogs + Cats along with Miss Chickie and Mr Froggins. It replaces the Wind-Up Toy from Nintendogs. It is a white mouse with a yellow wind-up handle thats makes the toy run along in a zig-zag pattern with a "squeak" sound. It can be bought from the Town BARC shop, available from the beginning, for $8. Both dogs and cats will play with this toy.
3DS: "Sir Nibbles has a magical effect on cats. Wind him up and play!"