If cereal is your favorite breakfast food a Cereal Killer Costume Accessory Kit for adults is perfect for you! The kit includes a light green fabric mask designed to look like a cereal box with a Cereal Killer headline and a bloody prop knife. Dress up with this costume accessory kit on Halloween and you're ready to munch on your favorite cereals! Adult Cereal Killer Costume Accessory Kit includes: Mask Knife.