The realization that the reason the entire conversation has been difficult to follow is because you're talking to an idiot.
"Of course, much of Kierkegaard's Religious philosophy can be traced back to his being a Taurus"
"Possibly, but... wait, what? You... Ohhhhhhhhh, I just had a Dumbpiphany"
The realization that the reason the entire conversation has been difficult to follow is that you're talking to an idiot, who is further claiming and/or asserting something which is blatantly unfounded or unintelligent; whereas before, you thought it was due to lack of understanding on your part.
Popularized as a joke from SMBC Comics; comes from an amalgam of the words "dumb" and "epiphany."
A "dumbpiphany" in action:
Jack: The reason my relationship with Sarah didn't work was obvious...she's a Gemini and I'm a Leo!
Frank: Well, yea- wait, what?! What about how you cheated on her constantly until she found out?