Bodystorming is a technique sometimes used in interaction design or as a creativity technique.
The idea is to imagine what it would be like if the product existed, and act as though it exists, ideally in the place it would be used. It is going through an idea with improvised artifacts and physical activities to envision a solution. This User Experience Design (UXD) technique is ideal to design physical spaces (e.g. the interior design of a shop) but can also be used to design physical products or software.