My neighbour's outside tap burst the other day, right after they left town for a bit. Guess what happens when you get Niagara Falls spraying against your house overnight in subzero temperatures?
And you don't want to know what icicles formed a few inches from the tap when the water's primary obstacle froze big enough to block it from the my wall. (well, you do, but I didn't get a picture of that.) Suffice it to say it took their plumbers an hour or so to chip down the resulting ice sculpture.