Um, how about racist. Taking a race, culture, society, especially ones that has been assimilated, colonized, oppressed and wiped out (kinda leaves white folks as the only ones standing, huh?) and reducing it to a few 'funny' characteristics then getting wasted is wrong any way you slice it.
This year seemed to me to have way more women dressed as in 'sexy squaw' costumes than I've ever seen (thanks Kesha and Urban Outfitters), the first of which we saw on our way home from a lecture on, wait for it, Aboriginal Perspectives in Art History.
Here are some amazing blogs that outline exactly why it is racist and totally unacceptable to appropriate culture and wear 'ethnic' costumes;
And, on a not-so-side note, this is the greatest thing ever.
(from Elusis at Livejournal)