— VOGUE.CO.UK (@BritishVogue) September 20, 2015
Yep, that's a bum bag worn as a crop top.
The MM6 Maison Margiela spring/summer 16 show transformed sequins into streetwear, which actually kind of worked in a weird 70s glam rock way.
— MandP Models (@MANDPMODELS) September 20, 2015
Bum bags were also used in the traditional fashion too, just in case you were wondering.