The Thais are very particular about touching, especially in public.
The head should never be touched, since the Thais consider it the most sacred part of the body. Farangs are notorious at ignoring advice on etiquette and I first visited my ex-wife's family in the country, we sat down for a long meal. The afternoon feast transformed into a drinking contest between the males. I had nothing to prove, especially since the lao whiskey was much weaker than White Lightning moonshine. The rice alcohol still packed a wallop to the head and I was more than willing to finish dead last in the mao kah Olympics.
I kept sliding into a sleeping position and my hosts continued to offer me glasses of the foul liquor. At one point the toothless old man smiled and ruffled my hair. I knew about the not touching the head thing and thought, "If you're drunk this rule is waived."
I returned the gesture.
The father was older than me. He can do what he wants. Plus he was drunk. He started shouting. I didn't understand Thai then, but his demeanor suggested that he wanted to hit me with something harder than his fist. It took forever to get the rice-cutting knife out of his hand.
"Khor-thot." I apologized dozens of times. My drunken contrition sounded more like khai-tot or Who farted?" in my boston-accented Thai.
The rest of the males laughed hysterically at the foolish farang. The old man simmered down after I bought two big bottles of lao-khao down and I swore to never touch a Thai person's head again. We drank those two bottles and then finished the beer in the fridge. Going to sleep I lay against the door. I wasn't taking any chances at getting chopped up in my sleep by a vengeful Thai.
The next day I woke covered with mosquito bites. My 'wife's father grunted a greeting indicating that his revenge mode was in gear. My hang-over was a killer, but my survival instinct ran strong and I avoided the gnarled rice farmer for most of the morning. Yung's muscles were knotted like tree vines. His muttering was unforgiving. His wife and daughter acted like everything was cool. As a man I knew better.
A little after noon the oldest brother showed up on his motorcycle and got off the bike to give his old man a motorcycle helmet on which he had written in Thai and English 'DO NOT TOUCH'.
Her father didn't find this joke was funny, but the helmet hangs on the wall ready for my visits and at least once during the stay someone will place the helmet on the father's head.
And Yung's doesn't think it's funny.
And I go to sleep against the door.
At least we understand each other.
And that's good etiquette.