Turnip glitch

From Wild World Wiki

The turnip glitch is a glitch in the game's programming. The glitch occurs when a turnip is placed on a table inside your house. The turnip (which would normally go rotten after a week) will stay fresh for as long as it is kept on the table, thus allowing you to keep it until turnip prices are high enough for you to sell it for a profit. To use this glitch, stand in front of a table and drop an item on the floor such as a shovel, net, etc. Then drop the turnip. The turnip will appear on the table instead of on the floor.