The Super Horn is an item that debuts in Mario Kart 8 (only appears in that game if not counting Mario Kart 8 Deluxe). It can block incoming items and slow down nearby opponents by the use of sound waves. One notable feature is the ability to block Spiny Shells, which other items cannot do. There is a rare chance that you will actually have the opportunity to use it; you can only use it once and then it suddenly disappears.
If you Listen Closely, You can hear the racer's horn