Halakhah for Kiddushin 87:21

One should take note of the Purim practice‏ ‏of men and women wearing clothing of the‏ ‏opposite ‎gender. No one protests this, but‏ ‏based on what I have written regarding‏ ‏attractive clothing, all ‎authorities agree‏ ‏that one may not do this with intent to‏ ‏resemble [the opposite gender]. R' ‎Yehudah Mintz already addressed this,‎‏ ‏saying that since this is done only for‏ ‏Purim joy, there is no ‎prohibition; it is like‏ ‏‎[a male] cutting the hair of an underarm or‎‏ ‏ervah to avoid pain. [Per Bach, a ‎male may‏ ‏not cut this hair for the sake of‏ ‏beautification. -‎‏ ‏MT]… In my humble opinion, R' Yehudah ‎Mintz's‏ ‏words are clearly overridden by those of R'‎‏ ‏Eliezer of Metz, who prohibited such dress‏ ‏even at weddings. We see that even when‏ ‏this is done for joy of a mitzvah, we do not‏ ‏compare it ‎to doing it in order to avoid pain[which is permitted]. Also, even doing it to‏ ‏avoid pain is permitted ‎only when there is no other way, but there are many other‏ ‏ways to create joy for a groom and ‎bride,‎‏ ‏and to celebrate Purim, without violating‏ ‏the prohibition of, "A man shall not wear‏ ‏the ‎garment of a woman, etc." There is no‏ ‏doubt that R' Yehudah Mintz would not‏ ‏have written this, ‎had the words of R' Eliezer of Metz not been hidden from him.‎‏ ‏R' Yehudah Mintz also wrote that ‎since one‏ ‏may grab food from others on Purim‏ ‏without being charged with theft, one may‏ ‏also ‎alter his clothing. This is shocking;‎‏ ‏regarding financial matters we do rule,"Beit din may declare ‎property‏ ‏ownerless" (Gittin 36b), and so the latter‏ ‏day authorities have written that one‏ ‏should ‎not summon people to court for‏ ‏Purim theft if it is kept within the norms of‏ ‏the city, as established ‎by the city's‏ ‏leaders… but no court has the power to‏ ‏permit biblical or rabbinic prohibitions for‏ ‏the ‎sake of the mitzvah of Purim joy!...Further, these people wear‏ ‏shatnez!‎‏ ‏Further, this causes men ‎to be able to pass‏ ‏among women, and women among men, for‏ ‏the purpose of adultery! Further, it ‎is‏ ‏particularly bad when they cover their‏ ‏faces with masks to avoid recognition!‎‏ ‏All we can say in ‎this is, "Leave Israel be;‎‏ ‏even invoke this principle regarding‏ ‏biblical prohibitions. However, every‏ ‏person who feels awe of heaven should‏ ‏instruct his household and those who‏ ‏listen to his voice, ‎lest they violate a‏ ‏prohibition on Purim or in gladdening a‏ ‏groom and bride. May blessing come to‏ ‏him, to remove stumbling blocks from‏ ‏the path of our nation, and no longer‏ ‏will they practice ‎inappropriate‏ ‏customs.‎