The Simpsons S8E23, Homer's Enemy.
I watched this legendary episode for the first time in 15 years, and fuck me, it's some dark, dark shit. The writers went full Brit humor mode and made such a meta episode that's uncomfortable to watch, yet hilarious at the same time. I knew what the episode was really about back then, but now it's even more brilliant. Top 10 Simpsons episode, mos def. They really pushed some buttons with this one, this was a South Park episode before the actual South Park.