The Kuribo's Shoe was an item that the Shoed Goomba enemy would have dropped randomly when defeated. Using it from the menu caused your character to obviously jump around in a giant green shoe like in SMB3. Unlike in SMB3, however, you could not attack while in the shoe, but you could jump twice as high. You could jump out of the shoe and can choose to pick it up again into your menu or jump back into it, but if you leave it off screen, it'll disappear or if an enemy found it, they would climb into the shoe and use it against you. Either way, you wouldn't have wanted to leave it unattended. Idle, jump, fall, as an item. Also, giant enemies like Iron Giant could not climb into the shoe, but it would get punted off screen when they contacted it.