Growing up I spent many a Saturday afternoon at the movie theatre. Back then 50 cents would get you into a triple play movie. Another 25 cents would give you enough popcorn and fountain pop to last the afternoon.
When my Dad was young, he and his two brothers would walk along the train tracks picking up chunks of coal that had fallen from the coal car.  They would sell the bag for 25 cents which would pay their way into the movies.   Now days a movie ticket is $6.99 for a senior ticket (which I always purchase) or $9.99 for adult fare.  Add treats and you are looking at close to $25.00
Because I’m frugal and I want to know what is in the food I’m eating, I make a bag of popcorn to take to the movies.   A bag of homemade popcorn cost pennies to make and is much more nutrional than theatre popcorn.
I start with 1/4 cup popping corn ($2.09 for a 900 g bag) which I place in the bottom of a plain lunch size brown paper bag. Fold over the top of the bag tightly a couple of times. Place the bag in the microwave for 2 minutes on high. As every microwave cooks differently, it will take you a couple of tries to determine what time is the best for your microwave. Add salt and melted butter (optional). Enjoy for mere pennies a bag.
Note: You can also add vegetable oil but I have not tried this method.