A while back an old, tired-looking dog wandered into the yard. I could tell from his collar (though no tags) and well-fed belly and the fact he was clean that he had a home. He followed me into the house, down the hall, and fell asleep on the couch.
My dogs didn't seem to mind and he seemed like a good dog and I was Ok with him, so I let him nap. An hour later, he went to the door, and I let him out.
The next day he was back, resumed his position on the couch, and slept for an hour.
This continued for several weeks. Curious, I pinned a note to his collar that I wrote: "Every afternoon your dog comes to my house for a nap. I don't mind but want to be sure it's ok with you."
The next day he arrived with a different note pinned to his collar: "He lives in a home with ten children -- he's trying to catch up on his sleep. May I come with him tomorrow?"