My most recent book, published by De Gruyter, was on Misunderstandings in ELF (see here). My PhD student, Ishamina Athirah, is now replicating the work but focussing just on Brunei English. This is providing some fascinating data about what features of Brunei speech may be hard for people from elsewhere to understand.
This morning we were listening to a recording of a Bruneian talking to someone from Vietnam, and the Bruneian said:
when I went to Brunei for good
which the Vietnamese listener did not understand.
Although most misunderstandings seem to arise because of pronunciation, this one is caused by the Vietnamese not being familiar with the idiom 'for good'. And if you do not know this idiom, there is no way you could work out that it means 'permanently'.
Sometimes idioms are really opaque; and this is a fine example. When we are talking to people from elsewhere, we should try to be careful about using opaque idioms that they may not know.
On the other hand, 'for good' is such a common phrase in English that we may not realise that others do not understand it. Furthermore, it is probably quite hard to immediately think up an alternative to 'for good' when we are talking to someone.