Just out of curiousity, how many of you can tell me what this is for?

Because I had to learn real quick on Wednesday.
Here's what happened....
A friend of mine from Kansas was in town {on her way back from living in Denmark and Germany for a few years} and came over for a visit. It was great to see each other, since it's been like 4 years. Our kids were playing together as kids can do when they don't really know each other but just play anyway. And we were chatting and catching up on things as two friends who haven't seen each other in 4 years do. It was getting toward dinnertime. The kids were out on the trampoline with their popsicles.
Then the kids came inside in a hurry. Amid the shouts of "It's broken! It's broken!" I noticed that the sprinklers in the front yard were on. {We had been out in the front yard the night before scraping off all the dead grass to prep for our new grass. And in the process Cuddles had observed his Dad turning on and off the sprinklers.} I shouted to Cuddles to turn off the sprinklers. Again they said, "It's broken!" Hmmm....what, I wondered could be broken??
As soon as I stepped out of the door I noticed *all* of the sprinklers were on and there were two conspicuous streams of water coming out from the little green control box. Mystery solved, I knew what was broken...And then I came to another startling conclusion: I had absolutely no idea how to turn off the sprinklers. Even non-broken ones.
And the panic began to set in.
The Professor was still at work, so I picked up the phone to get his advice. No answer. That man *never* answers when I need him to.
OK, think, think, think.
I went into the garage to try the programming thingy. {Yes, I am quite familiar with all the sprinkler system terminology} But the button was already pointing to off. I moved the dials around a bit just in case. But, no luck.

Back outside I went. {Well, somewhere in this story Cuddles was sent inside for a bath. And to "wait until Daddy comes home..." But that's a bit of a blur.}
And I'm still trying to reach The Professor at work. And he still doesn't answer. I'm hoping that means he is already on his way home. Then I take another look at the sprinkler control box and try to plug back in the little devices that seem to have been removed. But my strength is no match for the geysers that they have become.
Soon The Professor drives up and figures out what all the commotion is. He knows what to do! We just need to get the key thingy to go down the long skinny hole in the ground that turns off all the water. Minor detail: we ain't got one.
We try to borrow one from the neighbors. Nobody who is home at that point has one.
{Speeding up the story...} The Professor zips to Home Depot to buy one of those key thingys. Tiffani and her kids leave {after someone gets a car door closed on them} and finally some how the sprinklers get turned off.
My estimation is that the sprinklers were on somewhere in the vicinity of an hour. {The ground was still damp this morning.}
And that is why I forgot to take pictures of them coming to visit.