To this glitch you need to have two side by side water streams going up to the edge of a nether portal. Stand at the end of the water stream and place a dropper (NOT A DISPENSER) above the water create a redstone timer to drop your items into the water stream. EXACTLY when the items go in the portal exit the world and come back in, you will have the item in the dropper and if you go through the nether portal it will be there also. Try multiple times until you get the timing PERFECT.

Thanks