I remember when my sister had to go to the bathroom during the Return of the King. She didn't want to go, (to put it in perspective, she's probably as big a fan of the trilogy as I am, hehe) but since it wasn't even halfway, she had no choice. She ended up missing the whole scene where Pippin sang to Denethor, as Faramir marched on Osgiliath (the singing scene, for those who don't remember the names, hehe). I've never seen her run so fast though, hehe....
But, I don't really like the fact that they don't let you take outside food into the movies. Even though we usually find a way, it's still a ripoff, hehe.