Lately, my dog has been doing something that puzzles me: he is a 4-year old English Springer Spaniel. He is very friendly, except that he will bark at strange trucks entering our street. Anyway, we have had a houseguest for the past week (a female 28 years old). The dog barks at her when she leaves the house!
I’ve begun to notice this with other people as well …“Buddy” will greet people with tail wagging, yet bark at them when they leave!
Why should a dog be upset by people leaving the house?
Maybe he doesn’t want them to leave? If he’s made friends with them, he may think that barking at them will bring them back to pay attention to him.
Maybe her skirt was tucked in her pantyhose.
I once took care of a friend’s dog that did this. I would go over a few times a day to feed it, let it out, etc. When I would try to leave, the dog got noticeably upset and would bark at me. He didn’t do this when his owners were home, so I assumed he was just lonely, or had separation anxiety. Is your dog otherwise anxious when it is left alone?
Jeezarees, lieu. I got two stitches in my lip day before yesterday, and you’ve got me ripping them open laughing.
I second the “separation anxiety” thing. My cats do this all the time. They hate being alone.
Your cats bark? That’d be something to see.
Heh. Well, my cats ‘talk’ to people. Gomez is quite able to carry on a complete conversation with you, provided you don’t mind the meowing. And Ben just meows at you when you walk in the door, and when you walk out. He hates being left alone. 
My dog does this as well. When I come home for lunch (I live alone with the mutt), she’ll come up to me, tail wagging, etc. When I leave again, I tell her, “Be a good girl” and scratch her head, and she grrrrrrowls at me. I just growl back at her and laugh. My impression is that it’s because she knows I’m leaving and wants me to stay with her. I suppose it’s possible she desperately wants to rip my throat out and was just working up the nerve, but it seems unlikely.
When she was a puppy, we’d go drop my then-girlfriend off at work, and take the dog along for the ride. GF would get out of the car, dog would lean out of window and, as we drove off, HOWL at the top of her lungs, wanting GF to come with us. It was a little embarrassing in a crowded mall parking lot.
Short version: Yeah, I’d say the dog just wants everyone to stay with her and play and be happy.