I have one.
Here is a pretty good explanation of them.
The last time I was infected, I heard 'Take a Letter Maria' in my head, on and off, for 3 years.
God help me.. this time its Britney Spears singing Womanizer. I swear I have been singing Take a Letter Maria out LOUD trying to get rid of that other song which I cannot say the name of twice.
Hence, awake at 1am.