I was sitting at home one day when I felt a strong hunger overtake me. So I grab my keys and hop in the car. A quick glance at my gas gauge showed I had exactly half a tank. I drive a few miles over to the local burger shop, park, and head inside.
After I finished dining, I once again hop in my car to head home. After putting my keys in, I notice I now have a hair over half a tank of fuel.
How did I end up with more gas than I started with?
It sure wasn't the burgers.