Street style stars and celebs like Cara Delevingne, Lou Doillon and Rihanna are big fans and now it's officially trending at Paris Fashion Week. What is it? It's the slouch! Think of it as an evolution of the pajama shirt and your favorite boyfriend jeans, because they have paved the way for the slouchy head-to-toe trend. Think jumpsuits and classy oversized tops and trousers in luxe fabrics. As you can see, French actress and model Marine Vacth (right) has got the look down pat.