An interview is something that can make or break a career,so even if you apply for a position at McDonalds or for a higher position at any company , I think you should wear some black pants and a shirt,a suit, something that makes you look professional. The first impression is very important, so take into consideration this aspect too.
Here is a site where you can find some tips on how to dress for an interview: http://www.cvtips.com/what_to_wear_for_a_job_i nterview.html
I used to work in a training centre for the unemployed, we always advised the client to wear either a TuTu, a beige mac or if they are feeling really dressy, take a pair of curtains and make it into a Toga... you cant go wrong! Especially at McDonalds, they would snap you right up and pay the obligitory �2.39 per hour! Can I get a Woot Woot?