Being a Finkadink is much like being a dumb rat.(rat fink) If somebody is a Finkadink he or she is ratting on her friends very dumb-like. i.e. you are talking to the person you are ratting too while the person you are ratting on can hear you in the other room.
Did you hear how the mafia found out Jim? He was being a real Finkadink
Lieutenant of the Sleeping Travelers, Head of the Armed Forces for the Phenomenon Corporation, Knighted Elder Council Member of the almighty Yes Man. Eldritch abomination, Squid of the Oceans of Space. And I will have my vengeance, in this life or the next.