Why is Vogue Editor-in-Chief, Anna Wintour,  the real life  inspiration behind The Devil Wears Prada slumming on The David Letterman Show?

To promote the new documentary centered around her titled “The September Issue” -  about production of the 2007 issue was the best-selling in Vogue’s 117-year history.

Click to watch what the high priestess of fashion thinks about Dave’s socks.