There is no specific information about a "what katie did corset" in the search results. However, What Katie Did is a brand that offers a range of corsets designed by Katie, who has been wearing and designing corsets since 1995. The brand offers standard and extreme underbust corsets that can be used for waist training or fashion wear. Some of the corsets available include the Vamp Waist Training Corset, the Curvy Morticia Underbust Corset, and the Extreme Zita Underbust Corset. They also offer an Overbust Corset that can be worn as a top or under a sheer blouse for a 1950s pinup silhouette.