Actor-comedian Michael Richards’ explosive onstage use of the word “nigger” has ignited a movement to obliterate the term and substitute the euphemism “the ‘n’ word.” The idea has comedians debating the power of language, and some, like Dick Gregory, are pointing to the danger of sanitizing speech. ” ‘Calling it “the ‘n’ word” is an insult,’ said Mr. Gregory, whose 1964 memoir was titled ‘Nigger.’ ‘It should be just as much an insult to Jews if they started changing concentration camp to “the ‘c’ word” and swastika to “the ‘s’ word.” You just destroyed history.’ “