[UGAalum94]

Going with the "don't wear anything that you are uncomfortable in" that both KSUViolet and AGDSquirrelGirl (and FSUZeta) rightly mention, if you don't already own a sundress AND your campus really does suggest other possible outfits for that round, find out from members on that campus if you can appropriately wear something else more like what you would usually wear to a similarly dressy event.

Although you want to be appropriately dressed for your campus, there's probably a lot less of a sorority girl costume that everyone will be wearing than you might imagine. If you can figure out a way to wear appropriate clothes that you already feel comfortable in and know look good, why risk a certain kind of outfit you feel weird in? And I completely second FSUZeta's comment on the strapless deal.