I have a bowl full of bananas going brown at home, so once again dug through the archives for a solution. Turns out it's easy -- bananas separated at the top will ripen more slowly, because of a gas they emit called 'ethylene'.
This tip came from an experiment done in 2012, where three separated bananas stayed much greener than three that were still attached to each other.
Thanks to bananas' large surface area and relatively high production of ethylene (though many other types of fruits including apples, kiwi fruit, tomatoes, figs and pears also produce the gas) they have the ability to ripen other fruit in close quarters to it -- including things like avocado, that are not as commonly considered a fruit. If you do have a stubbornly hard avocado, you can chuck them in with your bananas, or put them together in a paper bag for quicker ripening.
Likewise, if you feel like your weekly fruit haul is all ripening before you get around to eating it, separate your bananas into a different bowl to keep them all from going bad too quickly.
Lifehacker's Classic Hacks is a regular segment where we dig up the most popular, useful and offbeat advice from our archives and update it for your modern lifestyle.