Since I was 7 years old, I have loved the holiday for this very reason. I don't know what it was exactly - the party has a simple premise: bring together neighbors to celebrate together in the street. But I always remembered it as the day when all the kids in the neighborhood could run around in the street with no cars, free to throw water balloons and raw eggs at each other with the only consequence being another thrown back in your own face. I always ended up looking like I'd been through a food war by the evening's end.
This year was the 33rd year, so it's become a long-standing tradition. The agenda includes bike decorating in the morning; parade in the afternoon; reading of parts of the Declaration of Independence; cook-out with hotdogs, hamburgers, and a plethora of red-white-and-blue colored foods; and finally the GAMES! - water balloon toss, egg toss, watermelon eating contest, and whatever else people think of, usually involving messy foods and liquids.