Kop Khun Khrap - I hate saying it!
For a word which is used with quite possibly more frequency than any other word in the Thai language - whose bright idea was it to make it three syllables and about as free flowing as somebody with a stammer attempting a tounge twister.
No wonder most Thai's and experienced speakers cut out the first two but why have the first two in the first place? 'Khrap' kind of says the same thing anyway.
If a Thai doesn't understand 'Thankyou' then a subtle bow of the head says it all - which reminds me, I also struggle with 'Howakalog' which is the Thai word for 'skull'.
What a daft un-sexy language it is. :)