I definitely think this is a thing! I get certain lines of songs in my head that repeat over and over. Also, lines from shows and movies in response to things.

I definitely have that! I also have mental tics, which are that but insistent and unvoluntary like physical and vocal tics.

Makes sense to me-- I experience that. Lines of songs or certain phrases/words I hear just get stuck in my head. My brain just clings to them. Can be for a day or a week. They come up randomly too, as someone here described, like a tic. I don't tend to vocalize them but sometimes I do, when I'm alone particularly or around my spouse.