(hex:55) is a glitch item in Pokémon Red and Blue. Its name is taken from lists of lift destinations. Using this glitch item will execute arbitrary code at A7D0 in the SRAM region.
With a specific series Hall of Fame corruptions, it is possible to manipulate the data here to do what the player wants upon using B1F, although the logistics of finding out which corruptions will work can be very difficult without a bot, and it can take many hours just to make simple corruptions that the player wants.