Phineas and Ferb (2007)

S02E48 The Lizard Whisperer

Phineas and Ferb discover a chameleon in their backyard, which unexpectedly expands to the size of a dinosaur due to Doofenshmirtz's Gigant-Inator. The enormous creature then strolls through the city. At the same time, Jeremy is teaching Doofenshmirtz a song that the villain plans to use in an attempt to call aliens to carry out his orders.