Let me say at the outset that the reason one or the other of the term “G string” was given to the type of breechclout worn by some Native Americans has never been definitely determined.
The early plainsmen who, apparently, were first to use it did not leave explanatory notes.
But I shall offer a conjecture: That which the American Indian used for a cord was, of course, a length of sinew or a strand of gut, and, naturally, such a strand tied around one’s waist to carry the single strip of cloth or flexible hide running between the limbs from front to back was of such thickness as not to cut the flesh.
Now, among any group of plainsmen in frontier days there was likely to be one, at least one, who toted and played a fiddle.
Necessarily having to replace its string from time to time, it would occur to him that the cord of the Indian breechclout might serve as the heaviest of its strings.
That would be the G string.