The one episode of Phineas and Ferb I don't like is the "Act Your Age" episode. It plays out like a bad timeskip fanfic.

Isabella gives up her crush, Phineas suddenly learns about the crush and realizes he likes her back, and Ferb randomly gets the girl of his dreams who happens to be much older than him and has been in a relationship with another boy she has great chemistry with throughout the season.

Yeah.... that's a little. Hm.