The mystery Water Cooler

Do you ever have one of those moments when something weird happens to you that you can't figure out. Tonight I was sitting here relaxing with the computer, the house was nice and quiet, the kids were all off to bed and out of no where the water cooler starts to chug water. Now no one has been near the water cooler for hours so now why all of a sudden does water start chugging down to fill the cooler? It spooked me out for a few minutes for sure so now I'm sitting here on edge.