Peanut
The Peanut is an item which serves two different purposes. One is that when Diddy Kong uses Peanut Popgun, Diddy Kong may charge his peanut popgun, and then fire an individual peanut out as a projectile. This peanut can be caught by another opponent and used against Diddy Kong, or yet another opponent. Diddy Kong can also fire peanuts from his peanut popguns by using his Final Smash, Rocketbarrel Barrage. These peanuts are faster, deal more damage and inflict more knockback, as well as being more rapidfire. A fully charged shot from the Peanut Popgun deals 17% damage, while a peanut inflicts 28% damage when fired during the Rocketbarrel Boost.
The other purpose of the peanut item is when Diddy Kong misses an opponent with Peanut Popgun or Rocketbarrel Barrage. The peanut will hit the ground and shatter. These shells can then be eaten like Food to heal 2% damage each. There can only be 4 of these shells on the stage at once.
Origin
Peanuts originated in Donkey Kong 64, where Diddy Kong could obtain the Peanut Popgun as a weapon and fire peanuts as ammunition. No characters have ever eaten the peanuts before, however.