At Hack A Day, I've learned of a new and impractical but fun snack: fizzy fruit.
The mechanism takes water-rich fruit, such as citrus fruits or, if scaled up, watermelon, and carbonates them in a method similar to the way that sodas are carbonated. High pressure carbon dioxide is diffused through the fruit, producing a fruit that fizzes when eaten like a soda.
Even better, all of the parts for this are available in a regular hardware store. A water-filter casing holds the fruit. Tubes lead to a CO2 canister, which can be bought at all kinds of places. (Apparently paintball guns have a good CO2 source and aren't terribly expensive.) Fruit's cheap in the United States, and all but the poorest houses have refrigerators to keep it cold.
The only way this could be better is if there was some way of refilling the CO2 yourself, but that probably requires a factory....