A song stuck in your head. Came from the German word, "ohrwurm," which means earworm litterally, and a song stuck in the head not litterally.

A term used to reference cannabis/marijuana/weed.

A song that sticks in your mind, and will not leave no matter how much you try.

The best way to get rid of an earworm is to replace it with another. Be prepared to become a jukebox.

Song that is stuck in your head

A song with an 'addictive' element (hook, melody, lyric) that draws people into listening multiple times. Song doesn't have to be good or bad, it just needs to have that 'addictive' element.

A song or tune that continues playing inside one's head, often to the intense annoyance of the particular head concerned. The song/tune will typically be of the hooky variety, making it easy to absorb and remember on just one or two hearings. Unfortunately for sufferers, it is often the most trite and irritating parasites (i.e. melodies) which attach to the host ear...

Etymology:

This was first coined, I believe, in Germany. The german translation is "Ohrwurm".

Most likely originated around the time of Hanson's "Mmmbop"; an ear worm refers to any song that is so catchy, and at the same time extremely annoying, that it feels like a worm has crawled into your ear and eaten the intelligent parts of your brain so that you hum the song all day long, no matter how much you hate it.