To get infinite amount of the 6th item in your storage in Pokemon Red and Blue. You must do these things:
1) Move the item to the 6th slot.
2)Go to Viridian City and listen to the guy that teaches you how to catch Pokemon
3) Fly to the Island with the 7th Gym on the Blaines Gym
4) surf on the right side of the Island, near the science building up and down
5) Run from the misingo that shows up, do not catch it is a big and will ruin your game if you catch it.
And you will have infinite amounts of that item, rinse and repeat as many times as you want.
Also that is a good way to catch Pokemon (Tangela, Starmie, etc.) Over of. 100