I remember, especially like when I was in high school, going to see like Dawn of the Dead and it was like mayhem in the theater and you could barely even watch the movie. It was so fun. ↗
If the pressure is getting to you, whistle. In a barely audible way. It's the best way I know of to let go of tension. Music gets your mind off the situation, and the act of whistling melts the tension out of your body. ↗