Fake ? Panel
From the Super Mario Wiki
Fake ? Panels, also known as Fake Question Panels or ¿ Panels , is an item that appears in Mario Hoops 3-on-3 which are the equivalent of the Mario Kart series' Fake Item Boxes. In the game they may be obtained from a ? Panel and once obtained may be thrown onto any part of the stage at will, once thrown they will appear to be normal ? Panels but with a flipped ? mark. Any player that touches them will be flipped over and lose any coins they may have.