MBFumo found in Zombies mode

I found this thing in 646 Broadway after unlocking the emergency exit, idk what it does but I haven't seen it anywhere else in the game before

https://preview.redd.it/3dhu1cebdi4g1.jpg?width=1920&format=pjpg&auto=webp&s=9b083df6109b0a9959c99c966fd88dbf17564aac