Snifit's Card Key
From the Super Mario Wiki
The Snifit's Card Key is an item from Paper Mario: Color Splash. It is used to open the doors of the jail cells and to operate the elevators in the Snifit Undersand Hideout in Mustard Café. A Snifit uses the card key to lock Mario and Huey in jail. The card key can be found under a couch, though Mario must fight several Snifits before he can collect it. After Mario collects the card key, he is able to use the elevators and free the Mustard Café Chef from his jail cell.