From Bulbapedia, the community-driven Pokémon encyclopedia.
8F is a glitch item in Pokemon Red/Blue that can be used for arbitrary code execution. Using it causes the program counter to jump to the data for the player's party. Since there is only a limited amount of data in the party, it is common to use scripts to jump to places like the item menu, where the player is not bound by the 6-Pokémon limit. 8F can be used to obtain otherwise unobtainable glitch pokemon, such as those whose sprites crash the game, as well as obtaining many glitch items. With enough code, it can even be used to program games inside of Pokémon.