I have had pizza, nachos and hot dogs at drive-ins, but never at a sit-in theater.
What I object to is a theater, I forget where, that serves “gourmet” food during the film (it was featured on Food Network’s Unwrapped). The last thing I want to hear at the movies is someone slurping down spaghetti while I’m trying to get watch the crapfest of the week.
But the wierdest thing I ever ate at a movie/drive-in? Texas-style barbecue! The drive-in owner’s snack shop had apparently closed (I assumed) and in order to keep things going, he invited people to come in and cook while the film was going on. The barbecuer had set up for 5 some-odd hours slow roasting this beef and was charging $5 for all you could eat!
I even got to take some home, since I ate so much!