Fluoride stare

The "Fluoride stare" is a popular term among conspiracy theorists for the look that normal people give them when they have said something bafflingly stupid. It is named after supposed poisoning that conspiracy theorists think normal people get from the everyone's favorite scary industrial wet scrubber byproduct, fluoride, in tap water.

The argument is essentially that, rather than the conspiracy nut being wrong, absolutely everyone else has been poisoned because to them, fluoride has been proven to be a neurotoxin by a single study that compared normal fluoride intake to higher-than-recommended fluoride intake and showed the world that, yes, consuming things higher than recommended levels is bad for you. How bad it is is the point of the study, not showing that properly fluoridated water can poison you.

Conspiracy theorists miss that point. The people that point out the issues of citing that study are brain-damaged, and the mountains of PubMed systematic reviews that show artificial fluoridation's safety are just made by other brain-damaged people. What fluoride conspiracy theorists actually see is likely a cross between their target's faith in humanity being partially broken and the thought "Oh dear lord not another crazy" before trying to escape.

As a rhetorical tactic
In reality, it is just a bad poisoning-the-well idea, like the shill gambit, in order to help with cognitive dissonance to communicate with the "in" crowd. It also functions as a catchy phrase to scream at debunkers. It allows conspiracy theorists to ignore or deny any information that conflicts with existing beliefs because everyone who doesn't agree is bought or has brain damage from fluoride. It's a neat little self-referential package where questioning of one's beliefs never needs to happen for those who tout themselves as often the most skeptical and questioning.

Which likely explains why so many have such vulgar reactions when confronted with facts, evidence, and cogent debates with those they have perceived as brain-damaged by fluoride. That's the problem when you start drinking your own industrial waste.

Dead wrong
The actual symptoms of are severe and don't generally involve increased skepticism of conspiracy bullshit.