Roasted, salted pumpkin seeds! Salty, crunchy, and they take a bit of mouth-work to eat (some people eat the shells, too, but those people are s t r a n g e. You can’t eat a whole lot of them due to the slow nature of the process, so they’re kind of calorie controlled. They go very, very well with cold beer, but ice water would work, too.
Or even better. Sunflower seeds. Those take much longer, and are every bit as salty. Or you could always try snuff! That will make you thirsty real quick. Rice cakes probably have 3 molecules of h2o per cake, so they are okay too. The thing is that it’s not a good idea to eat much salt though, but if you don’t care, try some olives…Think bar food, it’s salty and designed to get you to drink.
If it’s any help, my latest addiction is slicing up carrots and covering them in salt and garlic salt. Very tasty, and definitely makes you thirsty. 
Olives. One small olive has 4 calories and almost 28 mg of sodium, according to this website Calories in Olives - The Calorie Counter
If you wind up doing popcorn, I recommend popping your own. All you need is a stove, a big stainless steel bowl and some tin foil. Just put a little vegetable oil in it with a handful of kernels, cover it with the foil, and pop in a few holes to let out the steam. It doesn’t take any longer than the microwave kind, it tastes better, it’s cheaper, and you don’t get any of those nasty artificial flavorings. Just salt to taste and eat right from the bowl. You can also sprinkle on a little garlic salt or other flavorings you think of/find at the store.
mmm, these are good!
I would suggest light beer. Great fun drinking the beer, and after a few beers, water is wonderful!
Ok, you said food, but isn’t beer on the top of the food pyramid?
Lightly salted Edamame. It’s probably not the best on this list, but it’s up there.
Sliced jicama with lime juice, chili powder, and salt…mmmm!
The soy chips from Trader Joe’s would be perfect.
Now everyone must promise not to send a screen shot of this conversation over to the girls at the pro-ana sites. I swear I thought that’s what the OP was fishing for before I checked his earlier posts.
I’ll second pretzels, specifically the very hard pretzels.
I enjoy eating sliced and lightly salted, fresh, hot peppers or chiles. They are very low in calories and nutritious (High in Vitamin C). They will definitely make you thirsty and that ice water will seem truly orgasmic when quenching the fire. They also have the added benefit of acting as an appetite suppressant and perhaps a metabolic booster.
One of my favorites to eat this way, when I can get them, are fresh Green Poblano Chiles. They have just the right amount of spice (fairly mild) and are substantial and crunchy. Sort of like eating a spicy green bell pepper.
Quick sidebar…you being from PA, have you had the Unique Pretzels Extra Salt Dark Splits??? My new pretzel favorite!!!
I will search for and try them. Where did you get them?
I’m in NY, on the border, so at a local mkt here, but they come from Reading. I only discovered them around here maybe 2 yrs ago, at the most?
Those little, skinny pretzel sticks would work. I also like those little Kashi crackers; they come in a variety of flavors, and make you thirsty.
Salt and vinegar soy chips aren’t too bad for you and, boy howdy, you will enjoy your water too.
Sadly, most dry products are also calorie-dense.