S01E15 - The Third Wheel - "Luke Is A Happy Golden Retriever"

This could be it. The greatest Luke episode of all time. Whether he's playing video games, playing guitar, singing at the top of his lungs, or just trying to remember his resolution to stop punching people, Luke has reached his fullest potential with this episode. Also they do other stuff like go to a Rooney concert and Oliver gets busted for buying coke... but the important thing here is Luke!