I just unlocked the Halloween 2010 Badge.
In a post today Foursquare had announced about two new swarm badges: Super Duper Swarm (500 check-ins) and Epic Swarm (1000) badges.
But didn’t mention anything about the Halloween 2010 Badge. To unlock this badge shout out anything with “Halloween“. This badge might expire at midnight on 10/31/2010.
Let me know in the comments if you were able to unlock it.