I'm thinking that some people will just about try anything to get an extra in flight meal.
But seriously, in my day to day work I've known people sat there for ages talking to someone who they were unaware had died. One young girl in a care home had even changed a lady's nightdress blissfully unaware that she had passed away about 3 hours earlier at least and had rigor mortis setting in.
Mind you I've been on some flights and the person sat next to me might as well be a corpse for what it's worth.