I have a feeling I know what's going on, but want to make sure, so I hide in the bathroom (I can see the front door from there). Well, sure enough, out comes Harley, Corky and Missy. Corky and Missy sit down and look at Harley expectantly. Harley, the little ham that he is, makes a big production out of it. Tail goes up (cocked at the end), strolls slowly over to the door, gets behind it, and rubs against it hard enough to make it start to swing shut...hence the eery sound...that of course, makes all three cats run for cover!
This is also the cat that learned how to turn on the water faucet!