Pretending overconfidence in order to give weak-minded audience the impression that the proposed thesis is so undeniable that no one in their right mind would ever doubt it.
When making an argument, defenders of mainstream narrative often use an overly confident or even arrogant language (using expressions like: "no one disputes that", "everyone knows that", "don`t you even know that", etc.) making even blatantly flawed arguments sound much more solid than they actually are, almost as if they were matter of basic knowledge or some kind of self-evident truths; similarly, when attacking the opponents` arguments, they use to feign amusement and speak in a derisive tone in order to pass extremely weak and shaky retorts as if they were crushing rebuttals.
One typical way this tactic is used is to come up with some far-fetched and very unlikely explaination for a problem, treat that explaination as the only right answer just on the basis of it being theoretically possible, while at the same time belittling the opponent for not being able to come up with such an "obvious" answer by himself.
The purpose of this tactic is to instill the audience with the idea that only incredibly ignorant and/or stupid people would ever doubt the mainstream, indirectly telling them that that`s how they`re going to be treated were they to ever side with the "enemy"; since our contemporary society places a huge importance on apparence and social acceptance in spite of actual reasoning, this is very effective in preventing weak-minded people from questioning the authority.
Example:
Rather than saying: "It doesn`t feel right that all institutions would conspire against the people."
"Hahaha! Imagine thinking that ALL institutions would conspire against the people!" is said instead.