In any living language the change in meanings of the words and phrases is a natural phenomenon. But sometimes this change is very essential and a certain word or phrase loses its original meaning during the time and accepts a new meaning in the opposite direction. My question is about such idioms in English languages.
Question: Is there any word/phrase/idiom/sentence in English language which was offensive (respectful) in the past and is respectful (offensive) nowadays? Please introduce some references for the offensive/respectful usage of each word/phrase/idiom/sentence in the texts.