Do you follow a pattern when you leave the house? I do. First, I say to the dogs, "Sorry, no dogs allowed"
so they don't try to make a run out the door when I open it. (they know this means they're not invited)
But more important, whenever I leave the house, I make sure that as I'm leaving,
I alwys call out to my children (and my husband), "Love ya, bye bye."
It's short, sweet, and to the point, and I mean it every time.
They usually answer me back in like manner. It's a great way to leave the house. 

One summer day, my middle son happened to be on the phone at the time I was leaving.
As I was getting into my car, I heard his voice, except the front door was already closed.
Then I looked up, and there he was. You might see that he was still on the phone.

I think it was a girl...