Why do songs get stuck in your head?

Even if you hate the song it will still be stuck in your head! Like, I mean there are some awful songs that I hate that are always in my head!!!!

Why!?!?

But, there are some good songs that I can never forget...

NEVER GONNA GIVE YOU UP,
NEVER GONNA LET YOU DOWN,
NEVER GONNA RUN AROUND AND DESERT YOU.
NEVER GONNA MAKE YOU CRY,
NEVER GONNA SAY GOODBYE,
NEVER GONNA TELL A LIE AND HURT YOU.

Sorry, not sorry.

~~~

This is a desperate attempt for ideas XD

Eat ass, smoke grass and sled fast!
SLED GANG!

Ps. Watch the video.
It's an edit by Grandayy and it's fricking amazing