There’s a new algorithmic sheriff in the Wild West we call YouTube. And its sole purpose: shooting down the ranking of the bosom-flaunting reply girls who stirred up  the site's users—a contretemps we've called Tittiepocalypse.

By favoring time spent watching videos over the sheer number of cleavage-driven clicks, Google hopes to make YouTube a better place for both casual and hardcore users. Let’s call it the “reply girl rule,” meant to disfavor videos which emphasize the creator’s bustiness over their insightful commentary.

Announced in an official YouTube blog post and on the site’s help forums, the new algorithm now bases related videos—shown as suggestions when a user finishes watching a video—on “which videos contribute to a longer overall viewing session rather than how many clicks an individual video receives.”

The new algorithm is meant to reflect “viewer engagement,” which Google calculates by how long people stay on the site.

In theory, the new related-videos algorithm will hinder reply girl videos from reaching the top of related videos, because most viewers of reply-girl videos leave within seconds of realizing that there’s not much substance there.

“[C]licks aren’t always the best way to predict whether you’ll be interested in a video,” wrote the YouTube team in the blog post. “Sometimes thumbnails don’t paint the whole picture, or a video title isn’t descriptive.”

While the post doesn’t explicitly name the reply girls, the sentiment is clear. Reply-girl videos are designed to feature the YouTuber’s breasts prominently in the thumbnail; they are labeled as responses to popular videos, even if they don’t really address the subject; and they use tags to trick YouTube’s algorithm into featuring them prominently. After a large community outcry, YouTube labeled the reply girls as “spam.”
 
Alejandra Gaitan, whose channel, TheReplyGirl, is most prominently associated with the genre, has been anticipating the new algorithm for days.

In a video posted to YouTube on March 10 titled “TheReplyGirl and the new algorithm,” Gaitan announced she will continue to do replies for two weeks in order to “test” the new algorithm.

Gaitan says a recent YouTube redesign codenamed Cosmic Panda was supposed to stop video replies. Yet, she observed, “nothing happened, so I just want to test [the new algorithm] to see if it is not going to work any more for real.”

If the algorithm does prevent her videos from being viewed, Gaitan said she will “concentrate” her efforts on other video work. Near the end of the video, Gaitan gave a shout-out to the video-game commentating team Yogscast, one of the influential YouTubers who rallied the community to fix the algorithm.

“Okay, you win,” Gaitan said to Yogscast. “What else do you want me to say? You win.”

YouTubers, also anticipating the new algorithm, have taken to leaving disparaging comments on various videos uploaded by Gaitan.

“So exciting! Tomorrows the big day! The day when thereplygirl goes obsolete! Hooray hoorah! Your art is dead, and so is your income! Now go outside and get a job...” wrote kingaiden1997 in a top comment on one of Gaitan’s videos.

Of the dozens of reply girls operating in February, Gaitan is the last one standing. Megan Lee Heart, the most popular reply girl, recently claimed she was just joking around and making fun of the reply-girl phenomenon with her channel. LauraTickled, another notorious reply girl, deleted all her reply videos, and uploaded a 10-minute rant on another channel titled “YOUTUBE is FULL of SEXIST ASSHOLES.”

YouTube has been tinkering with the algorithm since at least last week. On March 9, various YouTubers responded to a YouTube blog post complaining about glitches in the system.