Honestly I don’t know if it’s something Lemmy-only, but I see many post titles ending with the world rule for no apparent reason
Just block the subs that do it and never waste another second of your life thinking about it.
It’s a meme rule
Le epic redditors i’d presume
It’s just a rule from those particular communities. You have to post something before you leave and it has to have the word rule in the title. It’s just a silly thing they do.
It’s a community an instance with a rule that if you log in to the website, you have to make a post before you leave (ie log out). The “rule” bit is people indicating that the post is because of the rule, and it caught on. Irritatingly enough.
It’s specifically 196, which comes from the reddit 196. If you see it elsewhere it’s just due to memeing
Getting a bit more in depth, it specifically stems from the r/195 subreddit, which had only one rule stating that if you visit the subreddit page you must post before you leave. This rule was carried over to derivative subreddits like r/196 after 195 shut down. When 196 came to lemmy, this style of post carried over.