The KC-135 Stratotanker's job is aerial re-fueling. One might call it 'a gas station in the sky.' The KC-135's can pump more fuel in 8 minutes that what your local gas station pump could if it were to run for 24 hours non-stop. Today, we're only unloading about 4,000 pounds of fuel but it could carry 208,000 pounds if needed.
The boom operator controls the amount of fuel off-loaded, they lie face down in the rear of the plane. After coordinating with the re-fueling pilots, the A-10 aircraft fly up, get their jet fuel and fly off.