You may not know it, but the DC area has a big Caribbean population. Every year they have a big parade/festival/party down Georgia Avenue, and this year's is on Saturday. It starts at 11 am on Georgia and Kansas and goes south past Howard U. There's a ton of huge and wild costumes, plus dancing, music, food and a craft fest. Here's their website, though beware it plays music.
If you haven't been before I highly recommend it. It's a crazy time: just check out the photos.