At christine kane's blog she's got a post, Readers Poll: The Uncoolest Song on Your IPod, with a long, and interesting, train of comments. One song that shows up on a few different comments is "U Can't Touch This" by MC Hammer (from the album Please Hammer, Don't Hurt 'Em).
I first got to know this song on various aerobic tapes (I've taught aerobics for years). I love the song, and it's appearance on any aerobics CD improves that CD vastly.
If it's "uncool" (or a "guilty pleasure"), it's a popular one, winning both the Grammys for Best Rap Solo performance and Best R & B in 1990. Pop culture-wise, it's also very popular as shown by the Wikipedia list of references.