Continually speaking a non mother tongue language can be tough sometimes and it can lead to some terrible disasters when you say something that you didn't mean. The sentence came backwards, up side down or the word that you mean to say you didn't say. Instead you said another which was the WRONG word to use.
I does not only apply to swear words or insults, it can be totally normal words. When it's totally normal words that screw you up the most, because you don't realise you said something that was out of order/wrong/rude. You just see a bunch of people looking at your oddly or angry..
I have a great example of that from our first visit to Australia.
We had come back to Australia for a holiday since ones of A:s childhood friends was getting married. The day before the wedding we where meeting up with the soon to be married couple and some of their other friends. I then went ahead and chatted a bit to A:s friend who's parents had been very involved in the planning of the event.
-Are your parents retarded.
He looked at me very strangely and answered in controlled but upset voice
-They don't seem to work so much.
Now I had obviously not intended to ask about his parents mental ability but more about whether they where still working full time, as in “are they Retired”.
I didn't realise what I said until afterwards, like a long time afterwards I just thought he was being really weird and angry.
So that teaches me to double check my wording.