It was in the last episode shown on tv. When Mysterion has the gun, Stan (Toolshed) says something like "Settle down, Kenny." I nearly shit myself when I heard it, rewound the DVR and listened again just to make sure I wasn't missing it. Good episode all around- they rarely, if ever, disappoint. Watched from the first episode on- once they started using computers the episodes became much more topical, giving the show new life. There has to be an end to the show eventually, but in theory it can literally run forever since it is simply a fun house mirror reflection of society's current issues in politics, religion, and pop culture. I hope Kyle's censored monolouge from episode 201 doesn't lead to the end of South Park- Matt and Trey have done a great job of bringing the show this far, and they have a show on par with the Simpsons for possible longevity.