On the evolution of language

From a Noel Coward song first performed June 1, 1931:

Mad dogs and Englishmen go out in the midday sun. 

From a press conference given by President Reagan, April 9, 1986:

Well, we know that this mad dog of the Middle East [Col. Quaddafi] has a goal of a world revolution, Moslem fundamentalist revolution, which is targeted on many of his own Arab compatriots. And where we figure in that, I don't know.

From a speech by President-elect Trump, November 30, 2016

We are going to appoint Mad Dog Mattis as our secretary of defense. But we're not announcing it 'til Monday, so don't tell anyone — Mad Dog. He's great. He is great.