on the bus in Thailand

'I went to Bangkok on Wenday by wan. On the wan, I saw some footbon and wolleybon players. They were wery tall. I think the awerage height was sik feet. Somebody told me that they were wery good players. I also think they wear ek-ek-el size shirts.'
This is what you hear from an average Thai who [tries to] speak English. They don't have /x/, /v/ and ending /l/. There might be more but these are the most obvious. They can't pronounce them, not even enunciate. As teachers, we want them to pronounce and enunciate the words clearly.
I was doing phonics with my 2nd graders today focusing on /ax/. Somehow they got the four examples I gave; ax, wax, tax and max. Now, I  moved on to /ox/ and I gave the word ox and box, and asked each one of the 30 kids to say the word loud and clear. Everybody shouted, 'ock, ock, ock, buck, buck, buck'! They still needed more practice so I corrected them. Then something unforgettable happened, I was in the middle of teaching and was really into it when I gave the word fox. Everybody started shouting the word and I turned red, asked them to stop, erased the word and used ox and box again. Guessed what they said?
They really made my day. The teachers were amazed at how the students were able to read, but I was scared somebody might have misheard it and think that I'm teaching them inappropriate things.
Ah well, lesson learned.