The Earworm is a character in the SpongeBob SquarePants series that is the cause of getting a song stuck in one's head. It appeared in the episode, "Earworm." Sandy is the first to realize SpongeBob has it and says that earworms can be a danger. What earworms are are little worms that make themselves at home in one's brain (in the episode, it was SpongeBob's brain) and plays a recording of the song over and over, and enjoys it (in the episode, the song was Musical Doodle). The only way to get rid of it/them is to lure it/them out with "another catchy tune." Mr. Krabs and Sandy attempted to help SpongeBob git rid of the Earworm (Mr. Krabs sang High Seas Chant and Sandy sang Life on the Prairie). Squidward actually played a good song on his clarinet and causes the Earworm to go to him. The Earworm got into SpongeBob by simply crawling through one of his holes. Probably like most victims, it gets into Squidward by crawling underneath the eyelids.
Earworm looks like a green cartooned worm. It sits in a rocking chair when it listens to its music. It is very similar to SpongeBob's tapeworm from the episode, "Pest of the West." Sometimes it wears a cowboy hat.