[JumpCrisscross]

> Is this a developing slang or have I just been under a rock and only noticed it now?

It communicates disagreement and pushback to perceived aloofness.

Its archetypal form would be an academic making a Monty Python Witch Trial argument being refuted by an average Joe. You generally don't see it followed by a rigorous intellectual argument, because by its framing it's rejecting intellectualism. Put another way, it's a call to common sense. In reality, it tends to reflect an inchoate argument,.