You use the item like normal by going into your inventory right clicking it and using it. Your player will then take it into his hands and use it. Once he is performing the action, you just simply click the red X in the inventory and take it out of his hands. This glitch also works by taking the item and setting it onto the ground while using it.

I have confirmed that this works with any food and any drink as well as blood test kits. I'm also very sure it works with bandages, blood transfusions, rags, and anything else that involves your player taking the item in their hands and going through the process of using it.