http://www.fursr.com/details.php?id=58&pid=58

[…]
The German word «Ohrwurm» stands for small insects. People believe that they crawl into human ears and start to live there («earwigs»). But Ohrwurm also stands for a piece of music that you hear and you can’t forget anymore. Melodies that come back into your conciousness when you expect it the least. And you can’t let them go. They are strongly connected with your emotional state and flow of associations.
[…]

Fuente: http://www.neural.it/