The Last Defense Lounge is yet another place on the U of C campus you can find a beer and a burger. But the somewhat more secluded location and brighter ambiance makes it my choice over the Den (which I am way too old to be in now) and the related Black Lounge.
The food here is actually pretty ok. They offer sandwiches, pizzas, burgers, salads and all the usual stuff with some things like fish tacos and rice bowls mixed in. Working on campus makes this a convenient place to have lunch, and I find the food to be a cut above the Den/Black Lounge.
So if you're on campus, stop here for lunch, and check out their daily drink specials. Some of them are pretty decent!