The mystery has been solved! The way to earn this badge is to check in to 3 venues tagged ‘parade’ in New Orleans.
You can expect to see “Show us your badges!” when you earn the badge.
How to unlock the badge has yet to be reported, but I am seeing a bunch of tweets of people unlocking the badge very recently, so some of you may know how to do this. Please feel free to share how you unlocked the badge.