What would you say is the toughest sitcom to have an encyclopedic knowledge of? "The Simpsons" is likely the first show that came to mind, considering it's been on for 23 seasons and will soon air its 500th episode. Maybe "Seinfeld" or "Friends," too. But a dark horse - possibly one ridden from Heaven by Thomas Jefferson - candidate is "30 Rock." Unlike "The Simpsons," "30 Rock" rarely has a coherent plot; the show's nothing more than a string of time-spanning jokes and pop culture references (everything from a porn parody of Amadeus called I'm-a-Do-Us to Liz getting mad at her mom for not marrying Buzz Aldrin because she could have been played by Laura Linney in HBO's Moon Wives), with dialogue so rapid fire that you remember individual lines more than actual scenes - and that's why it's so great.
To celebrate the beginning of the show's sixth season, which airs tomorrow on NBC at 8 p.m., here are the 15 Greatest "30 Rock" Pop Culture References. And if you've ever participated in a "30 Rock" Trivia Night: props