When fruits ripen, then produce the plant hormone ethylene. That can stimulate other fruit to ripen, if they are stored together.
Put the avocados in a paper bag with a banana. Then seal the bag and leave it overnight. The next day, the avocados are ready to enjoy.
To ripen bananas quickly, put them in a paper bag with an apple, tie the bag and leave it overnight.
Green mangoes will become ripe after one night if you bury them in rice. Rice helps keep ethylene gas in, rather than letting it escape, and that boosts the ripening of mangoes.
Peaches and plums
With peaches and plums, you only need to wrap them in thin towels and leave them overnight. The towel helps remove carbon dioxide from the fruits, and facilitates the entry of oxygen. This is essential for fast fruit ripening.