I have been coaching a friend lately who is going for their Thai citizenship and is drilling interview scenarios to make sure that:
1. He responds appropriately;
2. He projects the right 'image' of himself through HOW he responds in Thai;
YOU MAY BE A SUM OF THE WORDS YOU CHOOSE
Especially while people are learning a language, the person you are to native speakers of your own language may be a very different to the person you 'sound' when speaking to native speakers of the language that you're learning. This isn't to say that you need to speak perfectly in the language that you're learning, but there are some 'tells' - especially in Thai as to WHERE someone has learnt / acquired their Thai, and sometimes just the selection of words can make or break a situation ... and even relationship.
I once witnessed a westerner use the phrase:
phɔɔ dɛ̀ɛk dâi
with a client when she asked him at lunch 'How does it taste?'.Humour Doesn't Necessarily TranslateHe may have thought he was being humorous, but the reaction was as any Thai might expect. She was disgusted, got up from the table and told his director that she never wanted to have him associated with her account again. There is no real equivalent of the term แดก 'dɛ̀ɛk' in Thai - it is a low term used to mean 'eat' - usually animals. It almost sounds like the 'C' word in English (not the meaning, but the 'shock' value in hearing it in a normal conversation).
If you do have the desire to raise your Thai above just speaking on the street and use it for business or anything official, it's good to know how to say what you want to say in several registers.
This list here is a short one - but I think useful. ... Note the last term!
Note that some of the 'polite' terms are used more in writing - example บิดา มรราดา for father and mother, or สุขา for 'toilet'.Also, the 'less polite' word for 'toilet' ห้องส้วม is probably not said by many people - but I put it there as the word ส้วม (the actual toilet) evokes certain low / crass feelings.
Less Polite Vs. Polite or Written
รู้ | ทราบ
rúu | sâap
ไม่รู้ | ไม่ทราบ
mâi rúu | mâi sâap
ห้องส้วม | สุขา
hɔ̂ng suâm | sù-khǎ
กิน | ทาน
gkin | thaan
To Tellบอก | เรียน
bɔ̀ɔk | rien
Father Mother (Mum and Dad)พ่อ แม่ | บิดา มารดา
phɔ̂ɔ mɛ̂ɛ | bì-daa man-da
Husband and Wifeผัวเมีย | สามี ภรรยา
phǔa mia | sǎami phan-ra-yaa
Foreigner (Caucasian)ฝรั่ง | คน
fa-ràng | khon