Like the Nazis? You'll *love* their allies!... oh no, hang on, you won't.
There was that infamous Chinese "Nazi wedding" thing a few years ago:-
http://www.cracked.com/article_20584_the-5-most-absurdly-offensive-theme-weddings-ever-planned.html
http://www.chinasmack.com/2011/pictures/nazi-chic-cosplay-chinese-netizen-reactions.html
This seems to be more common than one might expect over there.
IMHO, the most effective way of making a point to Chinese would-be Naziphiles would be simply to ask politely how willing they might be to swap the costume with that of the Nazis' close allies. Then present them with the uniform of the Japanese army of the 1930s and 40s (of "Rape of Nanking" occupation infamy, et al).
I suspect that wouldn't go down nearly as well... which is rather the point. If they weren't deservedly offended themselves (or still too ignorant to get it), they'd probably understand after the response they received walking down a busy streetful of government propaganda-indoctrinated citizens.