It rarely happens. Last time i can recall was in Aston , Birmingham, my younger sister was with me. She was nearly assaulted and i lost it.
Never happened in Thailand until this evening.
Idiot trying out his EEnglish, trying to discuss some thing. Plato, i think. Well not a good idea.

"Have you read the Republic?".
I will be succinct.
It got worse, then into perilous waters Buddhism.
I had had enough of this idiocy. 
Then my son arrived , just asking for some money to buy food.
"Is that all you will give him?".
Sure, 
"You rich man,".
"Oh just f off, ".
Then he went towards my son and tried to touch him.
Something primeval kicked in , i lost it and attacked.  Not brutally, no need for that, just a warning. A slap and asked if he wanted more.
He ran.
Boy was there as back up.
We laughed.