What does "Like a jug that's googling out buttermilk" mean?

Reading "Adventures of Huckleberry Finn" on Project Gutenberg I come across a sentence I can't quite comprehend. Also, word "googling" caught my eye:

whilst he made all sorts of signs with his hands and said "Goo-goo—goo-goo-goo" all the time, like a baby that can't talk
...
The duke he never let on he suspicioned what was up, but just went a goo-gooing around, happy and satisfied, like a jug that's googling out buttermilk.

I would thought it's an OCR error, and something like "gurgling" meant instead, but there is a scanned page adjacent to the text, with the same word in print: http://www.gutenberg.org/files/76/76-h/76-h.htm

So, I am eager to know the meaning of the word "googling" in this context(this answer weren't of much help). Also, it would be nice to get the meaning of the whole idiom "like a jug that's googling out buttermilk".

Solution 1:

It looks like an example of onomatopoeia to me...that's the sound of (thick) buttermilk coming out of the jug.

(Unless of course it's a highly intelligent form of jug that is capable of time travel, using a web browser.)

Solution 2:

SUPPLEMENTARY to JeffSahol's answer:

Goo-goo, gurgle and google here are all onomatopoeic terms invented to imitate a natural sound.

Goo-goo is traditionally associated with the happy sounds made by babies, and that is probably what Huck means by goo-gooing around. Gurgle, according to the OED, is paralleled by similar words in other languages, and it is “not clear” whether the English word is borrowed or independently developed; words in Romance languages may have some relationship to the Latin gurgulio, gullet or windpipe.

OED does not give a comparable meaning here for google, which it regards as a variant of goggle; that in turn has two broad senses, as a variant of gobble and to stare with protuberant eyes. I would therefore think that the use here is Huck's own onomatopoeic coinage, with a reference back to the earlier baby sounds.