My Boston does the same thing with every single commercial. I find it extremely funny. He is not my first dog to do that. If you remember the show Frasier, one common thing in every single episode was that there was at least one instance when someone rang his door bell. I had a dumb dog at the time and every single time she ran to the door barking. On episodes where there were multiple rings she went crazy. I could never watch re-runs of the show late at night (11:00PM) because she barked at any time.