Cut a large watermelon in half. Put half in the fridge you can use it for that fruit salad you want to make later. The other half set on the tarp or plastic table cloth or whatever. Have your kids sit around the "watermelon bowl" and hand each of them a spoon. Then let them dig in. It's fun! you might even want to try a spoonful.
My kids loved this and your's will too! You can even turn this fun into an opportunity to teach your kids about taking turns and sharing. This activity is probably better for younger kids. Mine range from 1-5. Yes even my one year old was trying to participate. She had a blast and worked on her fine motor skills at the same time. My five year old called it. "a watermelon party" and repeatedly asks if we can do it again.
When you're done toss them in the tub or spray them off with the hose and throw them in the pool.
Now go have some homemade fun with your own kids!
A tip: If a half is too much cut a smaller bowl.
Also for my real young kids I strip them down to their diapers.