Really? Well its actually a really famous glitch in the game, You go to the guy that tells you how to catch pokemon in Viridian city, listen to him, after that fly too Cinnabar Island and swim up and down the coast (Near the Gym) then a missingno should appear. Its called missingno as its missing its ID number. Anyway Missingno will set your 6th slot item in your bag to 128, in other words if you have a Masterball as your 6th item, you will now have 128 Masterballs. Just don't catch missingno as it can cause graphical glitches, also make sure your 6th item isnt a key item (an item you can't delete), your bag will be filled with that key item if you do.