Theory that America is the only real country on Earth, could kick every other country's ass in a war (combined), has the right to police other countries and isn't a part of the United Nations.
Belief commonly held by Republicans.
God bless America... And fuck everybody else.
Referring to American people who have an impression of themselves and their country as being some how superior to the rest of the world. It is an ethnocentric belief that their culture, politics, economics, society and generally all aspects of the country as so amazingly awesome. Thus, the behaviour of someone who has a big dick. It is also the attitude for which Americans are often disliked by other nations and groups of people around the world. Rather than take a humble, helping, culturally sensitive approach to interaction with other people and international relations; the big dick syndrome often causes tensions with other peoples due to how non-Americans are assumed to be wrong or inferior. Also includes a denial of any possibility of making a mistake and an inability to apologize - leading to a lack of credibility and faith in the US by other peoples. The sydrome comes in part from the belief that the military's might is sufficient to over-rule any opposition. This might is used often in contrary to the principles of democracy, self determination and freedom which the country was founded upon.
American Big Dick Syndrome has been demonstrated in Iraq, Vietnam, the alleged "fair-trade" (two for me, none for you) much of Latin American politics, ignoring the United Nations, etc.