We were sitting in the car, and Dylan asked me how I tell how much gas is left in the car. I pointed at the gas gauge, and I said "full, and empty."

He stuck his fingers down there until he felt the plastic covering the gauge, and he said, "All you have to do, is break the glass, then point the needle at F, and you will have free gas. You'll have a full tank."

If only it were that easy. From the mouths of babes.