In our days, it became common to wear customs in Purim. Obviously there is no Mitzva or Minhag involved in this. It is just a folklore --of dubious origin though-- that became accepted in Jewish communities all over the world, especially for children. We must avoid however, and warn against, cross-dressing in Purim. It is an explicit prohibition of the Tora, Debarim 22:5: "A woman must not wear men's clothing, nor a man wear women's clothing, for haShem your God detests anyone who does this". If man dresses to look as a woman, wearing a skirt, or a wig, or using make up, etc... or if a girl dresses to look as a man, they are transgressing a serious Biblical prohibition. This prohibition applies even when one dresses to look as the other gender 'for fun' (R Obadia Yosef, Taz, Bakh and others) .
In Purim,today, we participate in a Se'uda, a festive meal of Purim. It is customary to serve alcohol, but it is NOT permitted to drink in excess. Purim should not be used as an excuse for drunkenness."In these days," declares Rabbi Weinreb from NCSY, a leading Orthodox Organization in America "when so many of our young people are prone to experimentation with dangerous substances, it behooves us to warn against the dangers of alcohol, especially on Purim". Quoting from Mishna Berura (sec. 695) on the laws governing the Purim SEUDA, the festive meal, Rabbi Weinreb emphasized that we are not commanded to become drunk, to look foolish and to lose self-control; rather, he said, we are commanded to become joyous" in a manner that results in love of God and thankfulness for God's miracles."
(See here the other Mitzvot of Purim)
READ THIS IMPORTANT LETTER from Rabbi Avraham Nissanian on alcohol and Purim