How come songs suddenly start playing in my head sometimes?

Like just now, Michael Jackson's "Thriller" just started playing, COMPLETELY out of the blue, I wasn't thinking of it, or listening to it (or any other music) it literally just came from nowhere.

It's as if my brain is LITERALLY an MP3 or iPod device that just started playing music by itself (like my iPhone does every once in awhile).

This is more common in my brain than on my actual phone, what is this?

Could I actually have a chip implanted in my head like that guy on Dr. Phil?

It is LITERALLY like my brain has an MP3 built in or something, it's kind of unnerving how clear and realistic (as if it IS an iPod or MP3) it is.

Is this even normal?

The government probably put radios in your fillings back in the 2000's when we still used radio technology, but now since we have the internet it's picking up the normal radio which is just music.

If you hear the song in your head, run to a radio and check to see if it's playing or is about to play.