Hard to narrow down to just one but I would have to say Osama Bin Laden Has Farty Pants is a special episode for me. It was one of the first episodes where I understood the current event reference since I was 10 at the time of 9/11.

T!? T-t-time to leave!?

It’s pretty subtle but the one in Scott Tennorman Must Die where Scott is showing the video of Cartman singing “I’m a little piggie” which causes Kenny to laugh himself to death. And the boys can barely utter “omg they killed kenny” due to their laughter. I just didn’t expect that scene to be a Kenny death scene it caught me off guard the first time. Definitely a unique one.