If the water and dry ice were somehow kept seperate until the bottle was moved I suppose it would last for a little while but it wouldn't last very long.
I agree it was a very stupid prank in this day and age.
Dry ice by itself will blow up a capped piece of heavy pipe. Dry ice (frozen C02) doesn't melt, it sublimes, converting directly from the solid to the gaseous phase. It will do this at most any ambient temperature found on earth, and at pressures well above the failure point of most pipe, let alone a plastic bottle. All it takes is enough C02 to last until enough pressure builds up to burst the container. I suspect the role of the water is to improve heat transfer into the CO2, thus speeding up the subliming and making the thing go bang sooner.