This is one of those rare pieces that, unless you're part of the very specific community it's aimed at, it'll only make sense to you on the broadest level.
In that sense, the simplest explanation for this is it refers to the online gaming phenomenon of the

UniqueEliteMonsterThat'sSuchAVanishinglyRareSpawnThatNotEvenProfessionalEliteLEvelPlayersHaveTheSheerLevelOfPatienceToGrind-PlayUntilItSpawns...

Well, in the world of Diablo 3, (which I played fairly regularly for a while after they ditched the online auction house), there was this achievement in Act V that you could obtain by encountering (and slaying) each super-unique spawn monster on the list (with the fancy-ass title of "collection"). Problem was that one of those monsters (a super-unique Zombie in the Act V cemetery), was such a vanishingly, infinitesimally rare spawn that even some of the most ardent professional players:

You know, the ones whose battle-tags are puerile, teenage fanboi 'sly' references to sexual positions, and who Twitch or YouTube stream themselves as they quite literally do nothing else all day long but play the game (well, other than the obvious breaks for bodily functions, or Cartman-screaming: "Mooooooom! Potty!")...

(Read the following lines in the voice of Deckard Cain):

"Well, even those aforementioned professional players put their slipper-clad feet down and told RNGesus that this was simply unacceptable as no mortal has that level of patience (unless you're playing the lottery or buying scratchers)."

(Read the following in the voice of Abd-Al Hazir, who is also the same actor, who did the voice of Raj's father in Big Bang Theory):

"So... After much prayer, RNGesus hit upon the idea of an order of Crusaders... er, rather, RNGesus hit upon the idea of dropping Gout Foot Johnson from the list of unique monsters in the collection for the "ooooh... Shiny!" Act V Achievement."

*****

So... This brings us up to a few weeks back, when, finding myself a bit bummed out, and creatively gummed-up for an hour or so... So, lacking any other inspiration of the moment, and knowing that perusing the news websites will only bum me out even more, I instead find myself firing up D3 for a bit of mindless hack and slash. Playing Seasonal Hardcore for shits and giggles, and now years past the point, where it might have still had even brief, ephemeral relevance to me on a game-geekery level, I find myself creeping through Briarthorn Cemetery ever-so-carefully with a still-squishy new HC character, and here is
Zombie...

Unicron... [sick-but-not-sic]

Gout Foot Johnson...

all larger than unlife and twice as ugly...

Neenur Neenur Neenur...

Braaaaaains...