Japanese: 箱ガンダム (Hako Gundam, "Box Gundam") or ダンボール ガンダム (Danbooru Gundam)
Easily the most powerful Gundam in the entire franchise, unrivaled in power, speed, and sheer intimidation factor. A true Mobile Suit masterpiece.
A cosplay parody inspired by American cosplayer Paul Palgen. The canonical Cardboard Box Gundam costume is made from a single plain cardboard box, with the word GUNDAM (all caps) written on the front, and exhaust ports drawn on the back, with a black marker pen. The costume does not seem to reference any particular Gundam or other mecha.
Nobody here but us chickens!