Water pistol? Seriously, goats do hate getting wet. If you could go through minus buckets, but armed with a water pistol a few times, she'd start to hesitate I think.
My dad has a little tennis-racket-thing which is battery powered and designed for swatting flies. It gives a tiny electric shock - nothing dreadful, you can touch it with your finger. But he says batting a bolshy tup on the end of his nose a couple of times with it, is sufficient to give them better manners.