I have heard stories of folks showing up in a muscle t-shirt.. don't worry, that confused me too haha..

I have my interview there next week.. and I think I'm going to do something along the same lines..

I would just wear something resonable like buisness casual. Suit pants with button up shirt, no tie. Khakis with button shirt, no tie. Something along those lines so you neat, but something comfortable. They aren't grading people on what you wear unless it is a tobacco stained and torn wife beater... which will defintiely get you in.