What is the definition of Reserves Fumes?

"Reserves fumes" is like when a gas station's fuel tanks get tired after a long day of spewing out diesel, but instead of just running on empty, they start to emit a pungent, smelly cloud of past-life memories and regrets. Imagine this: "After a grueling day of filling up at 'Fumes & Refills,' the gas station's reserves fumes decided to take a long, lazy nap, releasing a potent blend of yesterday's coffee and last week's bad breath."