Unique to Chicago, reasonably priced, early twenties. I'm guessing "reasonably priced" may be the key term. Unique to Chicago, reasonably priced, and early twenties SCREAM deep dish pizza.
You can find some pizza joint suggestions on this board. There were very recent posting's about uno's and due's
For a cut above, however, I'd suggest Pequod's Pizza.
For a non pizza dinner, I'd suggest a few margaritas and some interesting mexican food at Frontera Grill. There are people who think Frontera is over rated, but I've never been remotely disappointed there. I have been disappointed both times I went to Salpicon, however. Anyway, those are my two for $, early 20's, and unique - Pequod's and Frontera. Both are not far from "scene" areas for your after dinner drinks, also.
We cannot be friends if you do not know the difference between Mayo and Miracle Whip.