Popcorn is naturally gluten free, so always a good choice.
I love Butterkist, there are three 90 gram bags in the box for £2.15 (price from Sainsburys).
Salted is my favourite, and it's also available in two more varieties, sweet and butter. All you have to do is put the paper bag in the microwave for 3 minutes.
What is not to like? Perfect on a dark winter night with your favourite film.