Wayne Curtis in the New York Times:
Congratulations on selecting seat 21C! This manual is intended to familiarize you with the many options available to you.
Before BUCKLING in, please note that the man standing in the aisle next to you is about to make a request. He wonders if it would be okay for you to switch seats with his wife, who is in the middle seat three rows ahead. She is the one seated between the former linebacker and the canola oil salesman, and is peering over the seatbacks at you with wide and imploring eyes.
The man will ask this in a voice sufficiently loud that all passengers seated within several rows will look up from their sudoku puzzles and await your answer. If you say no, the passengers will all wonder: Why do you hate married people? You must be a bitter and
lonely person. Note also that there is no overhead luggage space three rows ahead, so you will have to wait for the entire plane to empty to come back and retrieve your bags. Have a good flight up at 18E!
More here.