[Boogieman]

Yeah, that works, but a couple refinements for you:

- add a cup or two of sugar. More sugar=more alcohol once it is done fermenting.
- put a large balloon (or UN-lubricated condom) over the top of the grape juice bottle. This prevents spillage, and gives you an indicator as to when the fermentation is finished. The balloon will inflate with carbon dioxide as the juice ferments, then the balloon will deflate once the fermentation is over.
- Pour the end result through a coffee filter to get rid of the yeast sludge that is left over, that will help a lot with the flavor.

[Carthego delenda est]

Excellent advice. That U.N. condom also acts as an air lock, preventing bacteria and other contaminants from entering, which leads to a bad fermentation. Hydrogen sulfide is one of the byproducts of a bad ferment. Very toxic (and smelly).

[TXnMA]

But -- be sure to add the sugar before fermentation starts!

How do I know? I can point you to a dorm room with grape juice stains on the ceiling... '-)