The combination is most unpleasant. Especially if you order butter. If you choke down a butter-sodden bitterly sodium-encrusted handful near the top, you can wash it down with a flood of caffeine cola. If you time your gulp just right, you can thwart the saltpeter after-taste before it fully registers. Then the caffeine jitters begin to take hold. So you pretend that your agitation is due to the mayhem and excitement on-screen, and begin nervously and compulsively ingesting popcorn at increasingly frequent intervals. You hope that the sodium-laden salt-lick will form a caffeine-absorbing buffer against the sugar-acid-caffeine content of the cola. You also hope the popcorn is hot to offset the bone-chilling effects of your mostly-ice ice-cold cola. So you eat several mouthfuls of salty popcorn without benefit of beverage until you are so gripped by sodium that you reluctantly reach for the corporate ice-water-caffeine concoction again and down a good dose of the throat-numbing, nerve-rattling, carbon-fizz antidote.
The popcorn is by now cold, so you gulp said beverage until the frozen cola is fiddling with your adrenals again. In an instinctive effort to minimize the damage to your kidneys, you find yourself clumsily swallowing handfuls of the sodium-encrusted cardboard buffer-staple, barely chewed in an effort to reduce the aftertaste, and vaguely hoping that the stomach will accept this sodium/caffiene banquet as some sort of a protein-fruit-juice combo. It was so expensive you had to finish it.