G-strings were a revealing bit of a garment invented by Humans for various reasons. The Deltan Duo wore a matching set of G-strings displaying the Starfleet symbol for their erotic performance at the Flag and Grog. (TOS novel: The Fearful Summons) Ensign Sara George flung her G-string at Tram Bir in the middle of her strip tease. (TOS novel: Spock, Messiah!)