I classify this as a cheat for Animal Crossing Wild World even though many would probably term it a hint. I think that if it is abused it can degrade game play and certainly alters the intended functionality. Either way, you can use these Animal Crossing Wild World cheats in any way that you find fit.
To make a ton of money on the turnip market you will need a friend whose DS time is different from your own. Have her check the turnip prices at Tom Nook's store and make sure that they are relatively high.
Now set your DS for Sunday and go and buy turnips at a low price from Joan. Load up your turnips and go and visit your friend's town and sell the turnips to Tom Nook there. If you can get a reasonable profit each trip you can easily make hundreds of thousands of bells in one day.
Remember that each trip will cause one of the animals in your town to move so be a bit careful with how you abuse this cheat.
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