This phrase is a notorious slogan found on stickers and T-shirts, used by people who oppose the policies of George W. Bush. The sticker also features a picture of W. The slogan is an anthem of resistance and refusal to accept Bush as America's legitimate President. It became more commonplace after the Iraq war started.
At the parking lot of a Media Play store I saw a purple car with a Not My President sticker on the rear.
by Starpunk September 18, 2007