I think the 196 community is the originator, though I already didn’t know what they were about when on reddit, I mostly find their posts confusing.
From what I understand the (only) rule is that the post title must contain the word rule.
The “rule” is just “if you visit here you must post”. Putting “rule” in the title means “i’m following the rule”. The rule was never enforced, it’s really just a memes forum with less judgement re: meme quality (they have to post SOMETHING to satisfy the rule, being a dick in the comments is working against the “rule”).
Really just a way to say “post memes, be nice” without giving all the “YOU can’t tell ME to be nice! I will be mean just to spite you!” people their beloved raging troll erections.