Only Men Wear Pink

Blue the boy's color, and pink is the girl's. That's just how it is.
Well... now anyway.
You see, back in the day ("the day" being one in the 1900's) it didn't really matter what color cloth you were wrapping you infant in. This was mostly due to the insanely high child mortality rate at the time (in the US at the time, about 165 babies out of 1,000 died). You would probably just end up burying the thing anyway, so why splurge on specifically-colored garments?
And supposing the infants did survive, all cloth inevitably becomes one color after the freak bowel movements of the little chillen'.

However, this type of seldom-seen gender equality just wouldn't do for Earnshaw's Infant Department. In 1918, they released an editorial that stated pink was "a more decided and stronger color ... more suitable for the boy; while blue, which is more delicate and dainty, is prettier for the girl."
What?
Yes, you read it correctly, pink was for the lads and blue was for the lasses.
And I guess it makes sense if you think about it, pink is the color of raw meat, bloodstains, and roses- manly stuff like that.

But there came a time when, much like the proverbial browned undergarments, the gender's stereotypical colors changed.
In 1927 Time magazine started a debate as to which gender should get which color. Because that was all people did in the 20's. It was woefully boring.
After years of needless squabbling, in 1940 people just said "to hell with it" and decided blue should be for boys, and pink should be for very effeminate boys.

In the end it doesn't really matter which color you wear, male or female. Except for brown. Both should avoid that.