While living in northern Thailand in the 1980s, I happened to mention to some Thai friends that I was planning a motorcycle trip to the far south of the country. They reacted with something like alarm. Why would I want to go there? Didn't I know about southerners? They were jai dam (“black-hearted”). They never smiled and were brusque and rude. And they liked nothing better than to string up a cable across the road at neck height, just to catch motorcyclists like me.
Despite their warnings I carried on and had a memorable trip. In those days a non-Thai traveler out in the provinces was a novelty, and I was the object of much curiosity and not a little generosity. I especially remember one day when a group of fishermen on the beach invited me to join them as they celebrated a good catch.
Then they saw the number plates on my bike. Had I really come from the north? Didn't I know about northerners? They were lai jai (“many-hearted”, i.e. duplicitous). They always smiled and would tell you anything you wanted to hear. Oh, and as for motorcycles, they had a special trick: a cable strung up across the road . . . .