Wow, this is an easy one. It's "You're getting old", that two episodes... It was my favorite 10 years ago, and I find it getting more relatable now. For reasons... well, it's very real, I've experienced similar stuff like Stan in thay episode, so_(:зゝ∠)_ (Oh and for a more cheerful answer, my second favorite would be "Good time with weapons' simply for how absurd this one is and the brainwashingly memorable song_(:3 ⌒ﾞ)_