I generally only go to one to two movies a year, so its a pretty big deal when I do. I get a large popcorn with a lot of butter and I usually have 3/4 of it gone by the start of the movie. My wife likes either pretzels / nachos with nacho cheese. I generally just stick to the popcorn now. I pretty much only drink water, and I get a cup and fill it up at the fountain.
Years ago, my wife and I used to make a meal out of it. I'd get a large popcorn with butter, nachos AND pretzel bites with cheese, and she'd get a soda. Sometimes when ordering all this food I'd say something to my wife that made it sound like we were meeting someone inside the theater...so we didn't look like such pigs.
Yeah, its expensive, but we go to such few movies and there is nothing like movie theater popcorn.