What is a "circlejerk," and how does it manifest in comment sections?

A circlejerk, in internet culture, refers to a self-reinforcing loop of mutual agreement where a group of people validate each other's views without any critical examination or willingness to engage with dissent. The term is borrowed from a crude physical metaphor and applied metaphorically to describe echo chambers where the goal is not to reach truth but to feel good about a shared opinion. Everyone upvotes, everyone agrees, and any comment that challenges the consensus gets downvoted into invisibility. On Reddit, circlejerks manifest in comment sections when a post attracts an audience that already agrees with its premise. In a subreddit with a strong ideological identity, a post that confirms that ideology will generate hundreds of comments rewording the same sentiment slightly differently, each getting upvoted by others who share the belief. No one is contributing new information; they are participating in a ritual of collective affirmation. The experience feels good to participants but produces little intellectual value. The circlejerk effect is amplified by Reddit's upvote system. Comments that challenge a popular opinion, even with evidence, often get buried below threshold because they are outnumbered by people invested in the prevailing view. This creates a distorted picture for anyone reading the thread: the most upvoted comments look like consensus, but they may simply reflect who showed up first or which community's norms happen to dominate. Reddit has addressed this culturally by creating explicitly labeled circlejerk communities — subreddits ending in "circlejerk" or "CJ" — that parody their parent communities by exaggerating their most common takes to the point of absurdity. r/circlejerk itself is a satirical space that mocks platform-wide circlejerking. These parody spaces serve as a pressure valve, letting community members make fun of their own tendencies toward groupthink, which is itself a nuanced cultural act.