Earworms - Mr T

Today I read an article in the Dominion Post called Winning the war on earworms (yes the one you have just read...) and it got me thinking...I have been fascinated by this phenomenon for years and haven't really questioned it deeply, unlocked it, got to the bottom of it.  The article didn't really answer it either but did provide a few insights (and reminded me about Joe Simpson, author of Touching the Void, and on our booklist, who describes an annoying earworm as he struggled to survive in the Andes).  How do you think they work?  Why are they hard to stop?  What is your most annoying tune that gets stuck?  I know my children have been driving me mad with a song every dinner time.  I feel like I know it (well the chorus at least) like the back of my hand but I have never actually heard a recording of it.  Quite often I hear some of your boys humming away to yourself as you play your own internal jukebox.  Is it amazing that we can use our brains like Spotify to store and retrieve literally hundreds of songs at will?  How can we 'hear' inside our heads?