Is it that bad? 

 I'll be honest and say that since I never have occasion to dress up, I don't really know what I'm doing there. I enlisted a couple of my female friends to help me get some clothes for the occasion, and that was the end result. I think I saw a couple other guys in khakis, though, so despite the fact that most of the people there were dressed better than I was, I don't think my sister will hate me forever. They're really nice khakis, if there's any redeeming value in that. 
Edit:
I have been informed that khakis are acceptable at outdoor weddings, which this one was. :shrug: