Earworm, a loan translation of the German Ohrwurm - is a portion of a song or other music that repeats compulsively within one's mind, put colloquially as "music being stuck in one's head." According to research by James Kellaris, 98% of individuals experience earworms.
This has been stuck in my head all day. I get that a lot, when I do I'm going to start posting them here. It could end up being a good playlist. Post your too if you like.