I was thinking about this last night for a long time, and there are
so many episodes that I could list as my favourite that trying to get me to pick one is almost cruel :P
But in the end after much deliberation, the one I ended up choosing for myself was "The One After the Superbowl, Part 1" (Season 2, Episode 12). It's the episode where Phoebe meets that guy who hires her to sing for little children, and she writes these horrifying lyrics that absolutely horrify their parents. I used to live for Phoebe's songs and the ones in this episode were some of her best work lmao. For those of you who don't recall:
XDDDDDDDD