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In Donkey Kong 64, Peanuts are used as ammunition for Diddy Kong's Peanut Popguns, and can be found scattered around the world in boxes. In Super Smash Bros. Brawl, a shelled peanut will sometimes appear when Diddy Kong uses his Peanut Popgun. This will recover a small amount of health if eaten. Other than that, the peanut doesn't do much else.
In The Super Mario Bros. Super Show! live-action segment "Two Bums from Brooklyn", Tommy Lasagna offered Mario and Luigi with a job of throwing peanuts at Brooklyn Dodgers baseball games, due to the fact that their skills weren't good enough to make his team. He threw each of them a bag of peanuts, which they proceeded to eat.