I’ve actually used it to delightfully disturbing effect on people IRL a few times, by doing my best crazed grin and reciting Jabberwocky. Surprisingly effective if done right! (For best effect, I use a slightly “off-kilter” sounding monotone and what TVTropes calls a “slasher smile”–you know, the kind of smile that tells people looking at it that at any moment you’re going to bite through their tracheas?)

‘Twas brillig and the slithy toves
Did gyre and gimbel in the wabe
All mimst were the borogh-goves
And the mome raths outgabe…
(insert insane giggle here)

Now if only I had a labcoat…

I think that that’s actually a pretty good representation of how Dave’s perception has gone wonky because he can’t deal with the knowledge that he’s Mad. The broken glasses are symbolic of the fact that he can no longer see “mundane” reality and can now only see the world through the filter of his “Mad”ness.

Or something like that. I’m not a Psychologist/Psychiatrist, nor would I even attempt to play one on TV.

I tracked down a LiveJournal comment by Mike where he says it is Jiggery Pokery. Those critters look like alien circuit diagrams.

“Buffering…” is one of those unique Shaenon touches, combining two parts silly with one part ominous.

Using an image of the cover of Narbonic Vol 6 as a key (although it’s a bit unclear), I can identify some of the characters Dave emits:
_ a s d l _ p _
_ n b v c _ _ l _
_ h g _ d s a p
o i u y _ _ _ w _
_ _ _ _
_ _
… which seemed unintelligible to me until I located the letters on my keyboard!