I heard a song on the radio a week ago, and ever since it is constantly in my head. It's there when I go to sleep and it's there when I wake up.
I've tried listening to other music - a bit of Tchaikovsky, Burning Spear, Motorhead, even Kenny Rogers and Dolly Parton, but as soon as there is silence:
Look at me I'm a train on a track I'm a train I'm a train I'm a chooga train - yeah.