I found LB’s idea of dropping something for the seatmate to retrieve amusing. It’s been some time since I last traveled by air (domestic flight, cattle class) and I don’t recall there being sufficient space between rows for anyone to retrieve anything other than stowed items beneath the seat ahead. Even then…
One memorable flight when I was on my to becoming a gadol hador (though not in the admirable meaning of the term) and I unintentionally – and embarrassingly – elbowed the rib cage of my seatmate. I tried folding my arms, but dozing off resulted in additional elbowings. My remarkably understanding seatmate’s somewhat less understanding aisle seat travel companion thoughtfully offered to punch my face in, but fortunately managed to distract himself with other things (tefilat haderech, indeed!).
From then on, air travel meant business class or bust (significant weight loss has also been suggested and is under frequent consideration).