A grating noise played over the radio when the DJ has decided that s/he is angry with the fans constantly calling in and requesting AC/DC.
U2 has been a known cause of traffic accidents world wide, but in spite of this fact, DJ's still manage to get a hold of CDs filled with U2.
The sound cannot be accurately described but as been likened by UNC Professor, Harold Fiske to "..that itchy feeling you get after getting stung by a bee, were that to be a sound". As a side note: 12% of the population is allergic to bee stings and 30% of that group are deathly allergic.
Tom: "What happened to your car, Sally?"
Sally: "Oh,I was listening to the radio and driving, and after playing 'Back in Black' and 'Hell's Bells', the DJ played some u2 so I hit a tree while having a seizure"
Tom: "Damn. I hate when that happens."