Silly String is a colorful, stretchy substance that comes in a can and is sprayed out in a foam-like form. It is made from a type of polymer, which allows it to expand and create long, thin strands. People often use it for fun at parties, celebrations, or as a playful decoration. When sprayed, Silly String can stick to surfaces and create a messy, whimsical effect. It is non-toxic and safe for children, making it a popular choice for birthdays and other festive occasions. However, it can be difficult to clean up, as it may require some effort to remove from various surfaces.