It can get expensive, buying a new Halloween costume year after year. But hey, that’s what we have friends for, right? Costume Swap Day is a holiday dedicated to trading old Halloween costumes between friends or other people you may know. You can do this by hosting a large event in your community, or simply by raiding your best friend’s closet one on one. Not only does this save you money, but it also helps the environment by eliminating the huge amount of waste produced on Halloween each year. This holiday is celebrated on the second Saturday in October.