Ok kiddo, sometimes people use a special kind of glass called goofus glass. It's called that because it's not very good at doing what regular glass does. It's not very strong, so it can break very easily, and it's not very clear, so it's hard to see through.
But some people like to use goofus glass anyway, because it looks pretty. It might be all swirly and colorful or have designs on it. It's kind of like wearing a cool outfit that might not be very practical, but makes you feel happy and special.
So goofus glass can be fun to look at, but you don't want to use it for things that need to be very strong or clear, like windows or glasses that you drink out of. It's more of a decoration.