rent free

Meaning

1. Said of a thought, image, or person someone can’t stop thinking about.
2. Used to mock someone for being unable to let something go.

“That one line from the movie lives in my head rent free.”

Where it came from

Built on the idea of an unwelcome tenant who doesn’t pay rent, applied to an intrusive thought. The full phrase “living in my head rent free” spread as a general internet taunt through the late 2010s and became a fixture of meme captions by 2020.