it says in the rid ฝรั่งขี้นก is [showing disapproval] a Thai follower of European of American customs; a Thai who puts on airs as if he or she was a Westerner; a Thai who apes Westerners
i had no idea it meant that i always heard it was used by thai people on westerners to literally mean bird shit westerner
i heard it was used by thai people on the foreigners who were back packers and stayed in youth hostels because they had no money. I was also told by a thai person not sure if he was being serious that it was used on foreigners with red/ginger hair because its the same colour as birds faeces which i replied birds faeces are black


