earworm: A piece of music that sticks in one’s mind so that one seems to hear it, even when it is not being played. Other phrases used to describe this include musical imagery repetition and involuntary musical imagery.
Saturday always seems to be earworm day. I blame Sirius satellite radio.
By the way, the earworm phenomenon is common in normal life and so may be distinguished from brain damage that results in palinacousis. Palinacousis is an auditory form of perseveration — continuing to hear a sound after the physical noise has disappeared. The condition is often associated with lesions of the temporal lobe.
Well I feel better. Thanks Wikipedia!