Phineas and Ferb - Season 2 Episode 4
Attack of the 50 Foot Sister

Phineas and Ferb create a slow reacting growth potion to help Baljeet with his "giant" watermelon, but Candace decides to use it for herself, when she finds that shes a little too short to be a flawless girl. Meanwhile, Perry must stop Doofenshmirtz from his most disgusting plan ever!