Stupid Evil Bastard has a list of things you should NOT do during the movie "Return of the King".
6. Finish off every one of Elrond's lines with "Mr. Anderson."
8. Talk like Gollum all through the movie. At the end, bite off someone's finger and fall down the stairs.
12. Every time someone kills an Orc, yell: "That's what I'm Tolkien about!" See how long it takes before you get kicked out of the theatre.
13. During a wide shot of a battle, inquire, "Where's Waldo?"
17. When they go in the paths of the dead, wait for tense moment and shout, "I see dead people!"