Ok here is a good myth I am sure you will all enjoy.
I work at a hotel and one night one summer people were tossing water balloons from a 14th floor balcony to the street below. One Balloon hit a car window and went right through it.
Does a falling water balloon have that much force and structure to go through the frond window of a car?
Ramp it up a bit more and can it go through the hood of a car?

you're sure it was a front window? the front window is laminated safety glass with a plastic membrane to prevent things from "going right through" it. the rear window is tempered safety glass designed to fragment on breakage to prevent sharp shards from flying around injuring people. when we cut apart a car to extricate a crash victim, we use an axe, or a special saw to remove the windshield, and it takes a while to accomplish.

I know that at a certain distance/height that hitting a body of water is like hitting concrete, it would be interesting to see if it works the other way around! (though i have my doubts)

maybe the water balloon was frozen?

a water balloon doesnt have much impact damage as it spread out till it pops. so i would think it will do the same amount of damage as a bucket of water poured from the 14th floor.