Actually, I speak fluent Thai, there is no word for Yes or No. There is ไม่ which is a negation word, and ใช่ which basically means "correct"/"right", not "yes". The Thai question format is generally: Q: Hungry? หิวไหม A: Not hungry. ไม่หิว A: Hungry. หิว

There are other question indicator words, but the one you're referring to is for "correct or not" type questions, e.g.

Q: This road, right? สอยนี้ใช่ไหม A: Right. ใช่ A: Not right. ไม่ใช่

Alternatively, for a lot of statements you can just respond with the polite ending words, ครับ for men and ค่ะ for women.

The question, "would you like one of these?" in Thai would be, "เอาไหม่"... literally, "want?". The correct response is then either: ไม่เอาครับ or, เอาครับ ... that is the polite form for "do not want", or "want". There is no other way to respond to that question (except without the polite ending).