(1) A jabberjaw is someone who never shuts up.
(2) A person who talks too much, to the point of ad nauseum.
(3) It is also a 30 minute cartoon created in the 1970s by Hanna Barbera. It used to be part of the Saturday morning cartoons. It was created with a format and writing that was similar to that of Scooby-Doo and Josie and the Pussycats.
(1) "You are such a jabberjaw; i can hardly get a word in edgewise."
(2) "Hey jabberjaw. Shut up! I'm trying to tell you something."
(3) "Do you remember that cartoon Jabberjaw? It's being replayed on the Cartoon Network now."