What is a niggly wiggly?

A niggly wiggly is a fictional creature often depicted as a small, furry animal with a long, bushy tail. It is typically described as being energetic, playful, and curious. Niggly wigglies are often used as characters in children's books and cartoons. They are sometimes associated with mischief and silliness, and they are often portrayed as being friendly and helpful to other animals.