Serious answer: it's an EPOS (Emergency Portable Oxygen System)
It's a plastic bag you stick over your head.
It's got a clear bit up front so you can see and a small oxygen tank in the back so you don't suffocate because you put a plastic bag on your head.
It's used for crewmembers to be able to get to a place with system oxygen before passing out in the event of an emergency.