Rosie suggested a hex might be one way of fixing her inconsiderate neighbours, so I immediately dived for Chambers dictionary, as I do whenever a word catches my eye. There are apparently three different meanings, and putting them together I deduce that we're talking about a hexadecimal bringing of misfortune, by a witch, using uranium hexafluoride. Is that about right?
The preceding word in the dictionary, by the way, is 'hewgh', which means 'imitating the whistling of an arrow', at least according to Shakespeare. The subsequent one is 'hey'. Why am I so enthralled by this stuff?