From Wiktionary, the free dictionary
butt floss (uncountable)
- (Canada, US, slang, derogatory) A pair of thong underpants or a swimsuit in the same style.
2004, JoAnn Ross, Out of the Blue, Pocket Books, →ISBN, page 369:"A woman doesn't put on butt floss and hooker heels to attend a garden party," Briggs said.
2013, Elana K. Arnold, Burning[1], Delacorte Press, →ISBN:I saw a flash of her white panties—real panties, not butt floss like Cheyenne wore […]
2013, Joanna Wylde, Reaper's Property, Ellora's Cave, →ISBN, page 83:“That butt floss,” he snapped. “Why the fuck are you wearing a thong to work at a daycare? Are you seeing him again?”
