Favorite episode: Just about all of them. Hard to say which one. I do like the one where Cartman went back in time and met Thomas Jefferson.
One of my favorite moments was when Stan was building a tree house and his mom and dad went through this little separation. Well, Stan asks for a cookie and his mom says: Yeah, Stan, that's how it goes! First a cookie and then next thing I know I'm not good enough for you! Go ahead Stan! Get your goddamn cookie!