Yep, McCain used it and pissed off Van Halen.
I think I’d go with “American Idiot” 
(for me, not you)
It smells like pee, in Alba-nee, New York
(nothing personal against Albanyans, I’ve never been there)
Most of the answers seem to be jokes, but I’ll go for a serious one: “Move On Up” by Curtis Mayfield. Classic song, postive message and not overplayed. Plus, it has that classic horn riff that could be a great brief instrumental introduction if I need to walk onto a talk show or something.
One problem though: “Take nothing less than the second-best” is not the most inspiring lyric, especially given that we’re a two-party nation. Two problem: I’m a young white girl, so I might be accused to co-opting the song. Three problem: I just realized this song was sampled in “Touch the Sky” by Kanye West.
On second thought, I’ll just go with Devo’s “Girl U Want.”
“Superstition,” by Stevie Wonder; partly to underscore my support of rationalism and secular government… but mostly just so I could enter a room accompanied by that funky blues guitar.
(I checked Youtube for a video of the song, and happened across this performance on Sesame Street. Yes, this was American children’s programming in the 1970s. Youngsters, you can thank the Moral Majority for rescuing you from this in favor of Elmo and Barney.)
I would use the song that has been my personal theme song for over 20 years now: Ace of Spades by Motorhead
[nitpick]
you got the lyrics wrong (bolding mine)
and you left out the most important part!
[/nitpick]