A Deku Nut is an item from the Nintendo 64 video game The Legend of Zelda: Ocarina of Time. In the game, the protagonist Link would find them early on in the Great Deku Tree's dungeon, where they would be required to kill the boss within the fortress.
The Deku Nut's ability is to stun enemies when thrown, after which Link will be able to attack the enemy.It is also the original way to kill Queen Gohma with it.
Deku nuts also appear in The Legend of Zelda: Majora's Mask, and The Legend of Zelda: Twilight Princess with similar appearances and uses.
Super Smash Bros. series
In Super Smash Bros. Brawl for the Wii, they are used to stun opponents. They can also stun the player as well. They return in Super Smash Bros. for Nintendo 3DS / Wii U.