As humorous as it sounds, there is actually such a thing as edible ink. Edible ink is a form of printer ink that will end up on some sort of food. Most commonly, it is used for cakes, where an image is printed and placed on top. HP (which is short for Hewlett Packard) does happen to make such ink cartridges, but they can only be purchased from certain websites.
Go to the website PhotoFrost.com (see the "Additional Resources" section) and click the "HP Edible Ink Cartridge" link. This link will take you directly to the HP ink cartridges available.
Select "Add to Cart." The page will now be updated, and you will be given a few options. You can either continue shopping, add more cartridges by changing the quantity number and clicking "Update" or purchase the item by clicking "Checkout." If you are done with your shopping, click "Checkout."
Click "Continue" again. You will now be prompted to input your mailing information, following by your billing info and how you want the cartridges shipped.
Select "Submit Order" and the order will be placed. You will then receive your shipment within several business days (faster depending on your shipping method).