I don't know what it is about fences that turns perfectly good neighbours into complete a55holes...!
My neighbour's dogs had eaten their way through to our backyard and after many attempts to patch things up, it was time for a new one. When I approached them, they were all for replacing it and doing the work together. But he didn't want to use a nail gun (on over 50m of fence...!!) and refused to allow my carpenter mate to help. Negotiations stalled at this point but their dogs continued to chew the fence. One afternoon, we returned home to find their dogs in our yard. My wife was trying to get them back to their yard when the neighbour accused her of beating their dogs. My wife is a dog lover and would never do such a thing however.... The next day, we came home to find half the fence torn down and the neighbours replacing it on their own. When I asked what he was doing he said he was doing his half and we could do our half. Then he demanded we do it within a month...!
My attitude took a nose dive at this point and I said I'd do it when I'm good and ready.
When I finally did it, admittedly without giving him any notice but he wasn't home so bad luck, he came home, found my mate giving me a hand as me using a nail gun. This sent him into an absolute rage and he verbally threatened me with physical violence, ON MY PROPERTY..!! I dared him to do it (would have gladly taken one on the chin to see him carted away by the cops for assault..!!) but he quickly backed away and went to his house where he cursed about it to his wife so loudly that the whole street could hear him.
Needless to say we haven't uttered a word to each other since.