Deuteronomy 22:5

Here are several laws in these verses which seem to stoop very low, and to take cognizance of things mean and minute. Men's laws commonly do not so: De minimis non curat lex - The law takes no cognizance of little things; but because God's providence extends itself to the smallest affairs, his precepts do so, that even in them we may be in the fear of the Lord, as we are under his eye and care. And yet the significancy and tendency of these statutes, which seem little, are such that, notwithstanding their minuteness, being fond among the things of God's law, which he has written to us, they are to be accounted great things. I. The distinction of sexes by the apparel is to be kept up, for the preservation of our own and our neighbour's chastity, Deu 22:5. Nature itself teaches that a difference be made between them in their hair (Co1 11:14), and by the same rule in their clothes, which therefore ought not to be confounded, either in ordinary wear or occasionally. To befriend a lawful escape or concealment it may be done, but whether for sport or in the acting of plays is justly questionable. 1. Some think it refers to the idolatrous custom of the Gentiles: in the worship of Venus, women appeared in armour, and men in women's clothes; this, as other such superstitious usages, is here said to be an abomination to the Lord. 2. It forbids the confounding of the dispositions and affairs of the sexes: men must not be effeminate, nor do the women's work in the house, nor must women be viragos, pretend to teach, or usurp authority, Ti1 2:11, Ti1 2:12. Probably this confounding of garments had been used to gain opportunity of committing uncleanness, and is therefore forbidden; for those that would be kept from sin must keep themselves from all occasions of it and approaches to it…

22:5 Adopting the dress and behavior of the opposite gender unnaturally blurs the lines between things that should be kept separate and distinct (also 22:9-11).