BBQ baked beans. Grab four really large cans of original homestyle Bush's baked beans, add 1/2 cup of yellow mustard, 1/4 cup of tangy bbq sauce, and one finely chopped onion and stir it all together in a very large pan and then bake until bubbly.
Or grab a couple of really large bags of rotini tri-color pasta, cook al dente and dump a bottle of Italian dressing on top. Add thinly sliced black olives or a crown of broccoli or really...any vegetable.
Or you can make a very large vat of potato salad with a 5lb bag of potatoes. I don't eat the stuff, so you're on your own with an actual recipe.
Um...let's see, there's also corn and black bean salsa. One huge can of black beans (rinsed and drained), plus one huge can of yellow sweet corn and petite diced tomatoes (drained), one diced onion, cilantro if you think people will like it and a bottle of italian dressing. Mix all ingredients together, let it sit over night and then serve with tortilla chips.