Chai Does Not Mean Yes
I want to explain a concept in the Thai language that is non-obvious and can be somewhat confusing to beginner Thai learners at first. This concept is rarely actually taught in learn Thai literature, and I myself only learned it after a confusing situation when getting food at a Bangkok food stall.
Chai (tone #3) does NOT mean 'yes.' Of course, if you look it up in the dictionary it is translated to mean 'yes,' and if you ask any Thai they will tell you it means 'yes.' But it does not mean 'yes.' Instead, the better translation would be 'correct.'
I repeat, the Thai language does NOT have a word to say yes! Gasp!
For example, if I were to ask in Thai 'are you hungry?' If you reply by saying 'chai' that will translate as 'correct.' Correct what? That makes no sense.
Here are a few examples of using the word chai improperly:
Example 1 (incorrect answer)
English: Are you a frog? Correct.
Thai: Bpen 1 gob 2 mai 5? Chai 3.
Example 2 (incorrect answer)
English: Do you want to go home? Correct.
Thai: Yaak 2 glab 2 baan 3 mai 5? Chai 3.
That response just doesn't make sense. Instead, if they ask a yes or no question, you need to take the key word from that sentence and use it as your answer.
Example 3 (correct answer)
Are you hungry?
Hungry (or not hungry).
Heu 5 mai 5?
Heu 5 (mai 3 heu 5).
Example 4 (correct answer)
Are you a frog?
I am (or am not).
Bpen 1 gob 2 mai 5?
Bpen 1 (mai 3 bpen 1).
So when would you need the word 'chai'? Actually, this word follows the same rules as above. If someone uses the word chai in a question, you will use it in the answer.
You have returned home already, correct?
Correct (or not correct).
Glab 2 baan 3 laew 4 chai 3 mai 5?
Chai 3 (mai 3 chai 3).
Now that you understand this concept, Ill leave it up to the extensive literature to explain the rest . . .
Good luck in your quest!