When girls play with Barbie and Ken dolls, they like to dress them up and play house with them. When boys play with Barbie and Ken dolls, they like to tear off their appendages. Boys couldn't care less if their hair is unruly. If their bangs got cut a quarter-inch too short, girls would rather lock themselves in their room for two weeks than be seen in public. Baby girls find mommy's makeup and almost instinctively start painting their face.
Baby boys find mommy's makeup and almost instinctively start painting the walls.
If a girl accidentally burps, she will be embarrassed. If a boy accidentally burps, he will follow it with a dozen fake belches. Boys grow their fingernails long because because they're too lazy to cut them. Girls are attracted to boys, even at an early age. At an early age, boys are attracted to dirt.