Funny things you've yelled in the theater

Now, I know that most of the time it's pretty rude and/or disruptive to yell something during a movie at the theater, but with the right timing and the right crowd, sometimes you can actually get a good laugh out of the audience. What stories of this sort do you have where this worked out, or if you're brave, when it might have even backfired? Use spoiler tags where appropriate if the movie's fairly recent.

For me, the movie was Indiana Jones and the Kingdom of the Crystal Skull. However, it wasn't during the actual movie but during the preview of M. Night Shyamalan's "The Happening". I'm a fan of Robot Chicken, so when the preview finished and showed the release date I exclaimed: "What a twist!" Granted, I think my friend was the only other I could hear laugh to that, but we still chuckle over it now.

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