Thong underwear or, less commonly, a thong bathingsuit. Synthesis of the English word "
fart" (a flatus expelled through the anus) and the
German word "halter" (holder). Likely a corruption of the
German word "buestenhalter" (brassiere). A synthetic colloquialism visually suggesting that the thong is able to "hold in" the expulsion of a flatus from the user's anus. (Army usage circa 1990)