Empty Water Bottle
Do you want to save money at the airport? Take an empty water bottle with you. In most cases, you will have to throw away a bottle containing the contents. To avoid this and spend a ridiculous amount of money on a bottle at the airport, simply bring an empty bottle.
Airports have fountains where you can fill your void with drinking water. Think of the money you will save by not having to buy water on the plane. It will also save your flight attendants time. Why bother them to get you a bottle of water when you could have pre-filled one yourself. It was the flight attendants who shared this trick, both for the sake of having a little less work and for the pleasure of seeing you save money.