On a LHR-JFK flight,as I boarded the plane,I came across a gentleman sitting in my aisle seat. (Coach...way before I'd heard of FlyerTalk).
I explained to him that he was in my seat and he tried explaining to me in broken English (with a Russian accent) that he wanted to sit next to his wife and his seat was in the next row.

Having lived in Russia for 6 years, I speak fluent russian and told him in russian that it wasn't a big deal and I'd be glad to switch seats.

The lady in the next row overheard us talking and says to her neighbor in an audible whisper, "Oh my God what are they talking about in that strange language?" I looked at her and she rolled her eyes in apparent disgust (!?)
Normally I could care less, because I've dealt with a lot of racism in my time in Russia but the whole eye roll just got under my skin.

Turns out that the seat I was being offered to switch for was also an aisle seat and it was all good.
I take my seat and a few minutes later she taps my shoulder and asks me in a voice dripping with honey, if I'd be "so kind" to switch seats with her, because she likes sitting in the aisle seat.

Needless to say, I refused.