It's Always Sunny fan reporting in. I love that show, and I've seen every episode about four times. I know most of the lines to the episodes at this point, and I occasionally quote the show accidentally in mid conversation. It also gave me my love for Danny Devito, as I can't get enough of the guy anymore. I was dying when he came out of the couch, butt naked, during the Christmas special.
The Nightman Cometh is easily my favorite episode. I also loved the callback to that episode during the episode with Thundergun Express when Frank is on the boat and recounts some of his adventures. The caricatures that result in the later seasons are especially funny, as Dennis has grown increasingly deranged, Mac more belligerent, Charlie more stupid, Frank more insane, and Dee becoming more and more the unlikely voice of reason.
As a side note, me and my friend at school, another It's Always Sunny fan, call ourselves the Gruesome Twosome. The pelvic thrusts and grunting generally follow after the mention of the title.