Nerdy Fact #1777: In the first generation of the Pokémon games, there is a glitch that allows you to go to Cinnabar Island and encounter a barcode-like Pokémon called MissingNo. (a normal/flying type), which allows the player to duplicate the item of their choice, including Rare Candy and the Master Ball. If MissingNo. is caught however, it can corrupt the data of the game and make it unplayable.
Source: Nerdy Facts