We've got a nozzle on the garden hose with one of those shower massage rotary dials that lets you select the shape and texture of your spray. It's pretty great, has everything you could ever want except a setting called Filthy Child. I don't know very much about these things, but I think the engineering would be a little difficult to manage. The Filthy Child setting needs wide enough coverage to hit a young torso in a single swipe, but not so much that you're wasting water. It would need enough force to work loose ground in dirt but enough delicacy so you won't take the skin off their thighs.

So, for all the engineers reading this--I'm putting out a call. Get me one of these, now!