"Doof 101" is a song sung by Danny Jacob and Laura Dickinson with the assistance of Dr. Doofenshmirtz for telling how he ended teaching in Danville High School in a parody to the theme songs of the 90s school-themed sitcoms.
Danny Jacob: He was the king of evil science
Until things went a little awry.
Laura Dickinson: Now he's turning over a brand new leaf
And he's not so bad a guy
Danny and Laura: Now he's got a second chance
And his new life's just begun
C'mon, it's gonna be fun
He's starting over at one
(Doof, Doof, Doof 101)
(Doof, Doof, Doof...)
Doofenshmirtz: Oh, we're gonna have a ball (Danny and Laura: Doof, Doof, Doof 101)
All the things I'm gonna show you
And this all takes place in fall
So don't let the timeline throw you!
I'm starting over at one
Doofenshmirtz, Danny Jacob and Laura Dickinson: Doof 101!