earworm

noun3

1. •
   A tune that keeps replaying in one's head or that one keeps thinking about, especially if unwanted.

   • The chorus [of "Meeting in the Ladies Room" by Klymaxx] spawned an earworm so potent that women still mutter it as they exit for a bathroom break twenty years later. — 2005
2. •
   Ellipsis of corn earworm (“larva of the moths Helicoverpa zea (syn. Heliothis zea) and Helicoverpa armigera, which are agricultural pests”).

   • I had planned in mind to tell you [...] how I protected, that is, guaranteed, Evergreen sweet corn against the bud worm and the ear worm; [...] — 1924
3. •
   (no longer used) An earwig; an insect of the order Dermaptera.