The Ancient Texts do make reference to a "brain in a jar".
This researcher was not in attendance, thus I only present the legend as it appears within the Ancient Texts, without editorial comment.
Methodology: MS Word Find was used to search for earliest mention of "jar". The following excerpts, while in date order, are taken from various forums and are responses to various threads.
Date: Wed, Nov 27, 1996 11:04 EST
From: MCODEV
"So what's the Buzzsaw going to do for us now, if we accidentally happen to be funny on these boards? Has this already been addressed on a FAQ board somewhere? Is there any value to being funny anymore?"
If you play nice, Buzzsaw will make sure that Lundy stays in his jar.
Date: Wed, Nov 27, 1996 15:33 EST
From: Lundberg02
I been lookinto this her quatum mechanic thing some more an I think I can git outen this damn jar
Date: Thu, Nov 28, 1996 00:10 EST
From: CLYaillen
Sure, where are you? Is your jar in orbit right now?
Date: Sat, Dec 7, 1996 14:10 EST
From: Akhilles
NEWBIE NEWBIE NEWBIE NEWBIE NEWBIE! HA HA HA HA!
Welcome aboard, but watch out for the dog. It has a throat problem. And stay away from the the jar in the fridge. It's Lundy's brain. Don't worry, you'll cawtch on eventually. Or else.
Date: Sat, Dec 14, 1996 20:08 EST
From: RUSSTUR
"Hoss! Lil' Joe! Mount up, Quick! Some side-show-freak-midget says that Pa's bein' held captive by a pickled Swedish brain in a jar! He wants four hundred dollars just to tell us where, you get the shotguns and I'll get the Sherrif!"