Phineas and Ferb Episode 20 - Put That Putter Away - Does This Duckbill Make Me Look Fat? >After watching an old sci-fi film, Phineas and Ferb decide to build a molecular transporter, which ended up switching the minds of Perry and Candace into each other's body after they accidentally go in together. However, Candace is forced to spend most of the day as a platypus while Perry (in Candace's body) goes on a mission to foil Doofenshmirtz's newest scheme; to replace the Mr. Slushy Burger jingle in the statues of mascot "Slushy the Clown" with his own evil jingles.