Student: Every button is programmed to pop, rock, and rap -- except the oldie's station for your parents.
Young Professional: Still programmed to rap, rock, and pop, plus the station that gives the traffic reports. As you approach the 30's, you'll probably also add the talk station that everyone at work talks about.
Established Professional: Will use the "scan" button and hear the first pop tune you learned as a kid on the oldie's station.
Approaching Middle Age: Thank goodness for "adult" pop, rock, and soul; will actually listen to the oldies for a few tunes.
Truly Middle Age: It's not that you're old enough to listen to the oldies, it's just that they keep playing songs you know.
Approaching Retirement: The radio is either on the oldies or off.
Retired: Stopped listening to the radio -- that "oldies" station started playing all of this "new music".