A Conversational Puma is a loud and opportunistic member of a conversation. The "puma" part comes from the person's tendency to "pounce" on you when you are trying to tell a story with loud interjections like "NO WAY" or "I KNOW". Though its debateable whether the conversational puma is truely interested in what you are saying or if he/she is just patronizing you, the story usually ends up being truncated for no other reason than to avoid being loudly interrupted.
This word was recently pioneered on the radio program Loveline
by Adam Carolla
Jesus christ, I hate that Suzy. I can't finish a single sentence with her without her pouncing on me with 'OMG' or something like that. She's such a conversational puma.