I flew down the east coast of the USA a few years ago. I was in the rear row starboard window seat. A behemoth of a man appeared (probably in his thirties) and occupied both the adjacent aisle and centre seats (yes, both and even then with some trouble - he needed physical assistance because he was almost as big in diameter as the seat pitch). The flight attendant brought seat belt extensions so he could strap in. I was essentially wedged in at that point and I knew that even asking him to let me out to use the toilet was going to be a big issue. When we were fed the evening meal, the greedy B asked for two!
I wondered what he was going to do in the event of an emergency evacuation situation. To this day I'm not too ashamed to say that I decided that if required I was going to use him as a blubbery stepping stone to get out and away.