Mario encountering a Balloon Boo in New Super Mario Bros.
Balloon Boos are a very large type of Boo found in only one level in New Super Mario Bros. for the Nintendo DS. They look very similar to a normal Boo except they can suck in air to make themselves huge. When Mario turns towards one it will stop and suck up air until Mario turns his back, then it will let the air out and glide toward Mario. If it runs into Mario he will take damage.