I was reading - Bicycling magazine's 1,000 all-time best tips : top riders share their secrets to maximize fun, safety, and performance / edited by Ben Hewitt, the other day.
One of the hints to riding in traffic was something along the lines of, "Be wary when you hear a car behind you approaching playing loud rap music."
Personally, if I hear someone blaring heavy metal, new country, Rush Limbaugh/Michael Savage, or hell, Wagner's Ride of the Valkries, I'm going to be wary. Loud rap music, though, that's when you really have to be vigilant. Thanks Bicycling! *sarcasm*