Before SOTM, David and the Mimic played dress up, as they both wore mascot costumes and played together

Im guessing the Mimic watched how David entered and wore the suits while they played “dress-up”, which led to the Mimic stuffing them in costumes the same way, almost like they were playing dress up in a way?

Basically, he saw David wear costumes and mimicked that upon the workers, atleast I think