The Fairly OddParents (2001)

S1E1 The Big Problem

Title: The Major Dilemma Plot: Frustrated with the limitations of childhood, Timmy expresses a desire to grow up and partake in adult activities. However, his wish takes an unexpected turn when "Da Rules" come into play, declaring that as an adult, he can no longer rely on Cosmo and Wanda for wishes or revert to his younger self unless he embraces his childlike behavior once more.