Ask HN: Startup "field day"?

I loved field day as a kid in grammar school. I know there is the occasional kickball tournament between startups in the bay area. I'd love to setup or do an all day long (charity benefit?) field day one weekend later in the summer. It would be fun to get all of us in one place and do something outdoors. If this gains significant interest, I'm okay with spearheading it up in my free time.