From the archives from 2/26/10
Adar 11, 5770
Rav ChasVchallilah Chinyok, of Bnei Brak paskened that one may not dress like a so-called modern “orthodox Jew,” even on Purim. In an interview with HaloModiah he explained:
Wearing modern orthodox clothing implies laxity on halachah, contempt for torah lishmah, the heresy of Zionism, and now, support for women as rabbis. In the past I have been lenient because we know that on Purim we wear costumes of goyim and others we do not emulate. It is understood that this is a joke, lehepech, to turn things around and do the opposite. Recently I have heard young people say that they admire the way those other Jews can have internet and train for parnassah. It has come to my attention through a choshov askan, who publishes kosher newspaper, that many of our youth were planning to dress up as modern orthodox Jews this Purim. The intent was not lehapech, but to sneak out and go to Internet cafes. Accordingly this year we will not allow modern orthodox costumes on Purim. There are plenty of goyish and animal costumes one can wear instead.