1. Drop any 1 space item on the Floor, ensure its in vicinity view.
2. Eat an item of food from within inventory.
3. Drag item on the floor on top of food being eaten
4. Items switch places.
5. Finish eating, food item is now on floor.
6. This can then be repeated.

This can be done with any item which has an animation when being used e.g. Drinks, bandages, morphine etc. Not a well known bug but it makes the idea of survival redundant.