This is a phenomenon that is experienced by people in all walks of life, and in many cultures, especially those with clock radios. In essence, it is when a lyric, set of notes, or any part of a song repeats itself in a person's thoughts, over and over, until the afflicted person is ready to either:
A: Shove a screwdriver through his or her ear;
B: Shove a screwdriver through the ear of the musician responsible for the song, or;
C: Sing the song loudly, thus infecting all individuals in the vicinity, and making them just a miserable.

Options A and B are generally frowned upon, and in most instances, punished. Unfortunately, this leaves most victims with option C. Suprisingly, little to no research is being carried out with the intention of finding a less harmful cure to the Song Stuck in Your Head illness.