I just spent some 20 minutes tracking down garn for a blog. While "go on" makes great sense, and it is easy to see garn as a corruption of that, but I found something as interesting, and I believe it may be a from a more direct source. See: https://en.wiktionary.org/wiki/gearn for the etymology." "Old English: Etymology, From Proto-Germanic *garną, whence also Old Saxon garn, Old High German garn, Old Norse garn. Ultimately from Proto-Indo-European *ǵʰorn-, *ǵʰer- (“tharm, gut, intestine”). A comment above called the word "vulgar," and I think references to the intestine very likely would be considered crude or profane. Also, in the meaning "go on," the term "go on" could just as likely be a corruption of the original Norse or German "garn." The trouble with language is that the sound continues down through time and keeps some aspect of the meaning, but becomes slurred and simplified. When the idea for written language was developed, our ability to compare information and record it down through time multiplied, I'm sure. For a word to be carried through time by the poor and uneducated people, it well may have a very old meaning, thousands of years as in this case. That of course is why the "anglo-saxon four letter word" avoidance rule came into existence. So many slang words go back to words with meanings like copulation or bodily elimination functions. Also, intestines are eaten by the poor in many places, but I have tasted it and I feel sure that nobody really wants to eat it. In the rural southern USA, the words are "chitterlings" and "tripe" for pigs' intestine or cattle stomach. Really poor and isolated people just can't afford to waste the protein. The word "tripe" in modern usage means, also, "worthless." This started as a word study, and ended up as an anthropology lesson. That's why I love language. It contains bits of ancient knowledge and lore, just as folk literature does. It's all wonderful in my opinion.