Recent episode with three foreigners hurt on the ground after a fist fight with three Thai tells we "guests in the nation" what not to do. The absolute rule is NEVER GET IN A FIGHT WITH A THAI. There are no reasons to do so except to protect your life, and situations are seldom like that. Drunk or drinking Thai men have their personal pride, their "face" enlarged and will fight quickly to defend it.
Rule is no matter what a tough guy you are at home, even if you have a shaved head and sweaty muscles popping out of your tank top shirt, if you are alone, you will be fighting THREE Thai; if you have three foreigners, you three will be fighting at least six Thai.
And the fighting style will be nasty from the Thai who has been street fighting since he was five. Elbow to chin or knee to groin style!
Best to defuse fast by doing whay, smiling, and saying COW TAUGHT, CUP, and walking away. Drunken Thai men, sitting on a street cafe, want The Foreigner to drink with them........ NO, no, no. Just rub your belly, make a sick face, do a whay, and say COW TAUGHT, CUP and Smile, even laugh. All at the table will laugh in commiseration and take another gulp from their bottles as you walk away.
Be nice and save your face--the real one and the prideful one.