Heading to Dana Point Harbor. A friend has a boat there where we're gonna bbq and watch fireworks. On the 4th, all the boat owners go out in the harbor in their dingies and have a water gun fight.
I picked some PVC pipe and miscellaneous parts and fittings yesterday and made a water gun that shoots about a gallon of water per shot (fires for about 5 secs). I also designed it to automatically feed from the sea water so I don't even need to take much effort to reload.
Poor little kids aren't gonna see it coming.