8 hours next/in front of a 'larger' person, knees poking your back, elbows sticking into your ribs, wheezing away...
Or
behind a fattie, who chooses to enlarge his/her space by
fully reclining his/her seat into your lap, so that there is enough space between his/her huge belly and the seat in front to lower the tray to load up with the food he/she finds necessary to sustain life for the next hour.
This happened to me on a BA European shorthaul a couple of weeks ago; 75 minutes of sheer bloody purgatory as this obese b******'s seat pressed hard on my knees. I could not lower my tray, even if I wanted to, nor could I move to restore circulation and avoid DVT without disturbing this inconsiderate lardarse's comfort.
And guess what? The b*gg*r had the nerve to raise his vast bulk enough off the seat to rotate his head and threaten me if I did it again!
The process of heaving his fat mountain up, and turning his head, must have taken 1-2 minutes. Emergency evacuation without endangering the lives of those behind him? Not a chance.