that would be the best trick ever. imagine how awesome you could be at sports betting? bet that team A will win.....wait until team B drank a bunch of water and then bam! turn all of the water in their stomachs in to wine so they got all drunk...guaranteed to lose.
hell, it'd also be the ultimate weapon. the human body is made up of something like 50% watert....BAM, turn all of that water in to wine and the person would croak instantly...it'd be hella easy to off a mother fucker.