No-poop guy will forever be the most upvoted post of all time in our hearts, even though he deleted his account and post and doesn't hold the title officially anymore.
The biggest catposting incident on lemmy was when people started "void posting" in cat community on lemmy.world.
Black cat images made it to the top of /all for several days. Here's the list of those images (lemmy search with cat community and with keyword "void"):
They don't have as many upvotes but a year-two back lemmy didn't have as much activity as now. Still made it to /all
Edit: edited query to sort by "old" to get the oldest ones first
Edit2: sorry, got stuck looking at the voidposts and realized the biggest incident was 7 months ago, so need to scroll a bit down with that query but you should also see the voidpost memes :)
Glad you found what you were looking for and happy to help! :)
I think it started in the cat community and spread elsewhere, but couldn't come up with a better query, sorry :( enjoy the voids!
Edit: and also some people have deleted their original accounts with all of their posts, so could be that we are missing the true numbers of voidcatposting incident
No, it was originally an August 2023 shitpost that was like "y'all upvote anything so here's a can of beans". That spurred the first wave of bean memes, and it has subsequently been trending every few months or so.