As you may recall, the 1998 action/horror comic book adaptation BLADE began in a slaughterhouse-turned-nightclub where the sprinkler system kicks on mid-party and soaks the dancers not in water but in blood. If you ever watched that sequence and thought that would be a fun way to spend a night out on the town, you might want to be in the Netherlands on Halloween night.
Anonymous organizers are planning to hold a Blood Rave at a discrete location in Amsterdam on October 31st with the intention of recreating the opening of BLADE and making it "more extreme". The organizers have developed a special spinkler system for the event that will be able to spray blood out over the crowd, and while the system has been tested with "a substance resembling blood", they want to use the real thing on the night. Where this blood might come from has not been specified.
I can't imagine the organizers will be able to secure actual human blood. Maybe animal blood collected from a slaughterhouse, but I wouldn't think even that would get past public health authorities. As much as the organizers want to shower people with blood, and although there are 3000+ potential partiers who are into the idea on their Facebook event page, I think (and hope) the people who attend are just going to be covered with red food dye.
Getting doused with blood of unknown origin (or of known origin) does not sound like my idea of a good time, but if you want to head out to the Blood Rave's secret location on Halloween and see what this is all about, tickets can be purchased here.