From the Super Mario Wiki
The Bunny Hood is a item in The Legend of Zelda: Ocarina of Time and, more notably, The Legend of Zelda: Majora's Mask, in which it makes Link faster if he wears it.
The Bunny Hood later appears as an item in the Super Smash Bros. series, starting with Super Smash Bros. Melee. It allows the player to jump much higher and move faster than normal for a period of time. One of the Special Brawl settings in Super Smash Bros. Brawl enables players to wear a permanent bunny hood.
Trophy information from the Super Smash Bros. series
| Super Smash Bros. Melee
||Don the Bunny Hood to improve your agility drastically, allowing you to jump great distances and move at high speed. The ears are a cute accessory: they're even adorable on characters they don't quite suit. The Bunny Hood was key in Majora's Mask, where it made Link move at one-and-a-half times his normal speed.
| Super Smash Bros. Brawl
||Headgear that hugely improves your jump and movement abilities. True to its name, the hood comes with a pair of cute, fuzzy ears. On the right characters, they're as cute as can be, but on the wrong ones, they're...scary. Of course, that adds to the item's charm. The sudden speed increase you get is responsible for more than a few self-destructs, so be careful.