The resulting conversation between two people with artificial, little or no intelligence. While it may seem like a normal conversation from afar, it actually makes little or no sense. Usually had between people who are convinced of their own intelligence, but in fact, have no clue.
A Furby (plural Furbys or Furbies) was a popular electronic toy released in 1998 with apparent "artificial intelligence" (AI). The toys were designed to interact with kids by speaking and responding to voices. The Furbies start out speaking entirely Furbish, a nonsense language with short words, simple syllables, and various other sounds. The Furbies are programmed to speak less Furbish as they learn more English over time.
When two Furbies were placed next to each other, they would respond to each other's speech. Because Furbies have no actual or inherent intelligence, one Furby merely responds to the other's noises with their own limited language. Over time this deteriorates into nonsense, hence "the furby effect".
Boss: So I've had a discussion with the project manager, and we both agreed you should have a larger part in this project
You: (Not happy about this decision made without your consent) Furby Effect!
Andrew: Did you hear the debate last night between Gillard and Abbott?
Migs: Yeah. They started off discussing their stands on asylum seekers. Then it went downhill, political mudslinging and criticizing dress sense....
Andrew: Yeah, politicians are prone to the Furby effect...
Grace: So I had this really deep conversation with Claire at the party last night, we talked about some pretty serious issues facing youth today...
Zones: Woman, you were both so drunk and stoned nobody at the party could understand what either of you were saying. Furby effect in action, baby.