Popcorn: almost as synonymous with cinema as watching the actual film itself, not least because of the sensory ambience created by the freshly popped smell. But popcorn as a cinema snack has a reputation for being pricey and at GBP £5 (USD $6.34) or sometimes higher for a large tub, it adds the pounds on to an evening at the movies, both health and cost-wise.
Source: Popcorn: Cinema’s Surprisingly Cheap Snack? – Celluloid Junkie