I do not have a source handy (working on it). But I can tell you that I looked in the Mishna Brurah, and the Rama writes that even though a man cannot wear women’s clothing (and vice verse), on Purim there is no issur, since they are only doing so because of the simcha of the day. Many m’pharshim argue on this, but it is clear that there is some type of inyan of dressing up. So much so that the Rama goes as far as he does.
Trust me on this, if it were from the goyim, the Rama would not say what he does.
For all thos who want to look it up, it at the end of Hilchos Megila (at the end of the Mishna Brura)