Perry the Teenage Girl

"Perry the Teenage Girl" song was altered from Perry the Platypus Theme and played in the credits of the Phineas and Ferb episode "Does This Duckbill Make Me Look Fat?", an episode in which Candace Flynn switches bodies with Perry the Platypus.The song was played during the credits, like when the original Perry the Platypus Theme was played during the credits for "Rollercoaster" and "Lawn Gnome Beach Party of Terror".

Lyrics
Female Singer: She's a semi-neurotic teenage girl of action!

Backing scat: (Dooby dooby doo-bah, dooby dooby doo-bah)

Female Singer: She's a feisty little redhead with a platypus' brain!

You best leave her alone,

She's playing MP3s on her phone,

And whenever she's around, you can hear the bad guys say:

Dr. Doofenshmirtz: Great, now I have this song stuck in my head!

Female Singer: She's Perry, Perry the teenage girl!