In Belgium we don't really have a Halloween tradition. A few years ago nobody was into it. Now you see more and more people decorating their houses, kids trick or treating at your door, cities organising events around this theme. But all in all it is still not 'the big event' it is in the US or UK.
But one thing Belgians, and certainly the people I know, are always into is drinking, and any reason is a good one. So the girls rented a cabin, decorated it spooky and sold lots (I really mean lots) of drinks. And having a drink with your friends dressed up as witches is my idea of a good evening :)