Every now and then, I'll hear a song that I haven't heard in more than a decade... And suddenly the words are being pulled out of my mouth from somewhere I don't know about and I can't stop it. Does this happen to anyone else? If so what song?

"This is the greatest and best song in the world"

“Rocketeer” Far East Movement. Great song and I always have to just either hum or quietly sing the lyrics.

Dock of the Bay by Otis Redding

Most songs by the Beatles. My mom left a album of theirs in the car today and before I knew it, I was singing pretty much every single song on there.

Come as you are - nirvana

A Day in the Life by the Beatles

Backstreet Boys lol My father in law was playing them at work one day and my husband came home and said "Son would dig them!" So we downloaded a bunch of songs and without realizing it I'm singing all the songs...I knew every word to every song and I hadn't listened to them in around 18 years. It took me back to being 7 yrs old, singing and dancing with my best friend, putting on concerts for our parents

Vicinity of Obscenity by SOAD

https://www.youtube.com/watch?v=ZamRD9LRZWE
"ONDEESE COMPUTERS
ISS $AVAGE
YOU GOT AUDEESE SOCIAL MEDIA A COUNTS, NICKA
BEEHIEN COMPUTERS, AUOUDO IS RUNYAMAUTH, NICKA
GON' MAKE ME POOL, A WISSUMSHUTAS, ACHA HOUSE, NICKA
LIKE WUSAH DASHICHU, TAUKIN BAU, NICKA"
-$avage
Really speaks to my soul.

Everybody, move your feet and feel united, WHOAAAAH

Iris by the Goo Goo Dolls, or like klymaxx said, the Backstreet Boys.
I really like bad 90's music!
Also, fun fact, 90's/early 00's pop music has a generic formula they used to calculate a song's catchiness to the human ear.

let it be by the beatles
incense and peppermints by strawberry alarm clock
i ain’t got rhythm from phineas and ferb
happy together by the turtles