butt floss noun a thong or string bikini with only a slender piece of fabric passing between the cheeks of the buttocks US
— Trevor Cralle, TheSurfin’ary, p. 17, 1991
— Judi Sanders, Kickin’likeChickenwiththeCouchCommander, p. 4, 1992
Young girls who sported thong swimsuits—known to Southern Californians as “butt floss” were “victims of a denigrating narcissistic society[.]” — Mark Sullivan, HardNews, p. 47, 1995