I had a friend who worked as a classroom support assistant in a school for children with learning difficulties. They were walking back from the swimming pool one day, accompanied by several parents, when one of the children used a few choice swear words. Mindful of the child's learning difficulties, my friend calmly explained to him that the words he had used 'weren't very nice' and that he shouldn't use them, whereupon his mother said (without a trace of irony), "I don't know where he f***ing gets it from, I f***ing don't!"