My dog does something strange when she's on the couch, it's not a behavioral problem, just funny and weird and I wonder why she does it... basically, when she's laying on the couch with us, quietly resting, or maybe chewing on her bone or a toy, she will at random start rolling on her back and "talk". By "talk", I don't mean barking, rather its a series of short, multi-toned vocalizations. She doesn't do this when she's laying anywhere else besides the couch. I'm not looking to stop the behavior because it's cute and funny and she seems to enjoy herself while she does it, I'm just curious as to why. Any ideas?