More ideas from Lady
Take a 2 liter soda bottle, and poke holes in it.  Hook your hose up to it, toss over a tree branch and turn on the water! This is basically genius. Kids will go bonkers.

Take a 2 liter soda bottle, poke holes in it. Attach to a garden hose. Toss over a tree branch and let hang for a kids water sprinkler. You can loop it over a tree branch and let kids bat it around for more watery fun!