see more

PARIS, FRANCE - OCTOBER 3: Fashion Blogger Julia Haghjoo wears Tibi trousers, and Birkenstock shoes on day 5 during Paris Fashion Week Spring/Summer 2016/17 on October 3, 2015 in Paris France. (Photo by Kirstin Sinclair/Getty Images)

PARIS, FRANCE - OCTOBER 3: Fashion Blogger Julia Haghjoo wears Tibi trousers, and Birkenstock shoes on day 5 during Paris Fashion Week Spring/Summer 2016/17 on October 3, 2015 in Paris France.  (Photo by Kirstin Sinclair/Getty Images)

see more

NEW YORK - FEBRUARY 26: Supermodel Heidi Klum launches self-designed Birkenstock shoe collection at Bryant Park Hotel Cellar Bar February 26, 2003 in New York City. (Photo by Evan Agostini/Getty Images)

NEW YORK - FEBRUARY 26:  Supermodel Heidi Klum launches self-designed Birkenstock shoe collection at Bryant Park Hotel Cellar Bar February 26, 2003 in New York City.  (Photo by Evan Agostini/Getty Images)

see more

STOCKHOLM, SWEDEN - AUGUST 31: Maria Jernov wearing a red suit and Birkenstock sandals and red Chanel bag outside Daisy Grace during the third day of the Stockholm Fashion Week Spring/Summer 2017 on August 31, 2016 in Stockholm, Sweden. (Photo by Christian Vierig/Getty Images)

STOCKHOLM, SWEDEN - AUGUST 31: Maria Jernov wearing a red suit and Birkenstock sandals and red Chanel bag outside Daisy Grace during the third day of the Stockholm Fashion Week Spring/Summer 2017 on August 31, 2016 in Stockholm, Sweden. (Photo by Christian Vierig/Getty Images)

see more

NEW YORK, NY - SEPTEMBER 04: Wardrobe Stylist Harrison Crite is seen outside the Duckie Brown show wearing a Cresedim vest, H&M shirt, Levis jeans, Birkenstock shoes with an Eric and Mike bag on September 4, 2014 in New York City. (Photo by Daniel Zuchnik/Getty Images)

NEW YORK, NY - SEPTEMBER 04:  Wardrobe Stylist Harrison Crite is seen outside the Duckie Brown show wearing a Cresedim vest, H&M shirt, Levis jeans, Birkenstock shoes with an Eric and Mike bag on September 4, 2014 in New York City.  (Photo by Daniel Zuchnik/Getty Images)

see more

PARIS, FRANCE - JUNE 26: Fashion blogger Thomas Reichegger wears Birkenstock shoes on day 3 of Paris Collections: Men on June 26, 2015 in Paris, France. (Photo by Kirstin Sinclair/Getty Images)

PARIS, FRANCE - JUNE 26: Fashion blogger Thomas Reichegger wears Birkenstock shoes on day 3 of Paris Collections: Men on June 26, 2015 in Paris, France.  (Photo by Kirstin Sinclair/Getty Images)