Chime Dog
A person - usually in a public forum such as a seminar or public speaking event - that likes to "chime in" unsolicited comments when the speaker is speaking or giving his or her presentation. That person's incessant chimes are reminiscent of a barking dog that impedes the natural flow of the presentation.
"Man, can you believe that chime dog in the pinstriped suit from this morning? 30 minutes in I wanted to tell him to shut the F* up and to put a dog muzzle on his face."