Anything. Grab a can of beans and a soda, you can use them endlessly if you follow these steps:
1. Open your inventory screen and open your bag. Make sure the food and drink are in your main inventory.
2. Right click on the food's icon and hold it for a few seconds.
3. Carefuly move your mouse off of the green "consume" button and onto the item's icon again
4. Double click the food icon and put it back in your bag, if you did it right the consume button should still be there
5. Click the button and you'll get the benefits from eating, only the food will remain :D