The Dunning Kruger effect is just that people bias towards thinking themselves more knowledgeable than they are when they lack expertise.
The brain is probably human, and maybe healthy, if Google image search is to be believed. I've had anatomy classes with very dead brains to look at and brains certainly look like that (?) but plenty of primate brains look that way, too.
I think OPs joke is that the second brain is the same, only measured differently because of said bias.
It's likely everyone in the comments have limited expertise and thus may be demonstrating said effect by correcting one another.

I'm still not getting the joke but I think it's funny enough that us commenters of commenters are questioning things and might be the only ones not experiencing the Dunning Kruger effect. Lol

[–] MossyFeathers@pawb.social 2 points 23 hours ago

Ye, I got that part, OP's response was what threw me for a loop, but I think I understand what happened with OP's response.

guy calls out op, believing OP's brain to be fake (in more ways than one, if you catch my meaning)
OP doesn't know much about human anatomy either, thinks "shit, what if they're right and it was mislabeled? Fuck, how do I recover?"
OP decides to play the fool, pumping up their self-confidence under the assumption that smokinliver is correct, thereby satisfying the Dunning-Kruger effect.
OP decides to add a bugs bunny clip as a "wink wink, nudge nudge" (to indicate they're not being serious)
no one gets it and everyone thinks OP is a moron and a dick.

I remember trying something very similar when I was a teenager which is how I learned that playing the fool is not a good recovery method lol