I'm going to talk about political correctness today because it's a subject we all have to deal with at one time or another in today's society.
Let's start off with the definition of the term:
noun - "Avoidance, often considered as taken to extremes, of forms of expression or action that are perceived to exclude, marginalize, or insult groups of people who are socially disadvantaged or discriminated against." via Wikipedia
With that established we can move on to the controversial part.
Example by Jeff Deist via The Mises Institute -