The ability for boys/men to make random sound effects from an early age ... Brandt has already started doing this. He has seen us fill our water cups from the water dispenser on the door of our refrigerator and now he puts his sippy cup in the dispenser area and goes "shhhhhh", as if to make the water sound. Then he proudly takes a sip of his milk.
I don't know ... maybe girls do this, too. But it seems like little boys start with the sound effects from an early age.