No, it’s not a conversation in a taxi. I don’t think it is even a real word. If you are really interested, it is derived from Greek words and suffixes combined in what is highly likely to be an incorrect and possibly even inappropriate manner. “taxidi” supposedly means “travel”, “voyage” or “journey”. Of course that explains why taxis are called “taxis”. “ia” is a suffix used for “state of”. You know about “logue” from words like “travelogue” and “dialogue”. The fact that most will read “taxidialogue” as “taxi” and “dialogue” rather than “taxidi”, “ia” and “logue” (OK I lost an “i” for aesthetic purposes) is neither here nor there and might possibly make sense if you engage with me by responding to any posts I may or may not make.