As a rule, I don't listen to top 40 radio. I said rule, not law, though. I usually listen to the Current or my iPod but occasionally I break down and listen to something like KDWB just so I'm not completely behind on what's on the radio. Sometimes I'm pleasantly surprised and hear an independent group starting to get mainstream play. Other times I hear songs like Rhianna's "Umbrella."
This "song" is on loop in my head, the annoying way that umbrella seems to be pronounced um-ba-rella and the echo-y part (ella, ella, ella eh, eh, eh). I've tried listening to Beck and Rilo Kiley, I've tried to listen to some catchy oldies, nothing works. It's one of those songs that's popular not because it's good but because it creeps under your skin and stays there and you need to hear it so you at least have a verse to go along with that grating bridge or chorus that you remember after hearing it two times. This is what I get for listening to a Clear Channel station.
ETA: Yesterday in the lab they had the radio on KDWB and sure enough there was umbrella. I didn't hear it today but Rehab by Amy Winehouse came on and one of my coworkers hates the "no, no, no" part of that song. The radio is working to drive us all insane.