I had a similar experience with an overly friendly/intrusive stranger on a flight from Indianapolis to Cincinnati 8 years ago. The gentleman next to me insisted on trying to engage me in conversation despite my clear unwillingness to talk. I had been up all night and this flight was the first leg of a long journey to London, so I was in no mood to talk. I tried to make it as obvious as I could that I wasn't interested in conversing, but he asked me about almost everything ranging from where I was headed to what my parents do. Eventually, I just closed my eyes and ignored him having exhausted my limited supply of one-word answers to his questions. I got the feeling that he was a little taken aback by my rudeness, but as I said, I was very tired.
Being British, I'm not sure if this comes down to a cultural difference, but I can tell you that I am not likely to strike up a conversation with a stranger in a setting like this even in the best of times. I only wish I had replied as Lennier did; the mention of a terminal (contagious) illness likely would've gotten me out of that situation a lot sooner.
