R.E.M.’s 1981 debut single “Radio Free Europe” is one of the undisputed classics of American underground rock, and its title nods toward a different kind of underground communication. R.E.M. named the song after Radio Free Europe/Radio Liberty, the American radio networks that beamed their braodcasts into Soviet-controlled countries during the Cold War. R.E.M. aren’t an active band anymore, though they’re …