good god this happens to me all the time... luckily I sing while I work often, and pass on each stuck tune to my co-workers, then get another one stuck in my head later. They're grown to hate me for it
It's like I have some weird radio station in my head - I 'll be working, then all of a sudden start singing the theme from Fraggle Rock or some equally obscure song. I don't mind so much though
passes the time at work