I am sure you remember the movie Passenger 57… There is a scene in which one of the bad guys gets his neck broken while seated in his airplane scene and then they cover his head with his hat to keep the cabin crew from asking questions too early. I was reminded of this scene when I found a passenger covered head to legs next to us on a recent flight to Madrid.
Luckily in this case the situation was less sinister, the young lady sleeping under her coat was alive and well as evidenced by the second photo taken after the “coat” changed position.