Phineas and Ferb find a chameleon in the backyard, who grows to the size of a dinosaur, thanks to Doofenshmirtz's Gigant-Inator, and takes a walk through downtown. Meanwhile, Jeremy teaches a song to Doofenshmirtz, who plans to use it to summon aliens to do his bidding. / Phineas and Ferb build a robotic rodeo in the backyard. Candace tries to prove she can focus so she can go to a concert with Stacy. Doofenshmirtz stalls to finish his entry into the Inator Creator competition.