Orðsifjar dagsins (reyndar bara ein orðsifj):

G-string:
1878, geestring, "loincloth worn by American Indian," originally the string that holds it up, etymology unknown. The spelling with G (1891) is perhaps from influence of violin string tuned to a G (in this sense G string is first recorded 1831). First used of women's attire 1936, with reference to strip-teasers.

(Í boði etymonline.com)