11. The Dressed-Up Sweatpant — We're guilty of rocking this trend a little too hard at work. But, getting to wear sweats in the middle of the day? Priceless, we say. Opt for a more pant-like silhouette and fool your boss by pairing the tailored cotton with a real shoe (as opposed to those ratty gym sneaks). No one will ever know.

Zara Plain Trousers, $59.50, available at Zara; Acne John Cotton-Jersey Sweatpants, $210, available at Mr Porter.