What is a "bobble hat"?

A bobble hat is a type of beanie hat that features a pom-pom or a bobble on top. It is usually made of wool or acrylic, and it's designed to keep the head warm in cold weather. The bobble on top of the hat is often made of the same material as the hat itself, but it can also be made of synthetic fur. Bobble hats are commonly worn for outdoor activities such as skiing or snowboarding, but they can also be worn as a fashion accessory. They come in a variety of colors and designs, and some even have patterns or prints on them.