Cinco de Mayo: Margaritas, happy hours and a burro Town Tavern's annual Cinco de Mayo party features a real burro on its patio. (2011 photo by Fritz Hahn/The Washington Post) Cinco de Mayo is traditionally the biggest party day between St. Patrick's Day and Memorial Day, with dozens of happy hours, concerts and parties around the area. We've put together a guide to our favorite events , and whether you're looking to taste exquisite Mexican cuisine, listen to an up-and-coming salsa band, enjoy a margarita at a rooftop happy hour or spend the night dancing on a bar, there's a party out there for you. And, hey, if you just want to get your picture taken with a serape-wearing burro in Adams Morgan, you can do that, too.