@jcrm Lol - I figured out how to do this accidentally. You may have noticed that Jailbait doesn't appear in the top bar anymore.
It's because I posted this to it (sfw and 18+ by a long shot, but you'll still want eyebleach). Apparently that top bar of communities prioritizes those that have no posts. Take a look - you'll see every suggested community is empty. Posting to one removes it from the selection algorithm.
Pinging @ernest as it looks like the sorting on that top bar algorithm is achieving the opposite of its intended purpose.