foursquare now has a badge to reward users that like to hang in large crowds late at night.
Find Out How Many People Use Over 1,000 of Your Favorite Social Networks, Apps and Digital Services
Check-in to a venue with 50 or more other users checked in after midnight (it actually sounds a bit difficult) and you will get your shiny new foursquare Players Club swarm badge and receive the following message:
Stranger danger! It’s after midnight and this place is swarming. Make some new friends!
Enjoy and try to stay out of trouble earning this one!