Because they don't have any. So oxygen can get to their brains. A snowwoman is easier to make, 'cause with a snowman you have to hollow out the head and use all that extra snow to make its testicles. So men can remember them. God created man before creating woman, because you need a rough draft before creating a masterpiece.
Diamonds are a girl's best friends.
Dogs are man's best friend. Single women complain that all good men are married, while all married women complain about their lousy husbands. This confirms that there is no such thing as a good man. E.T. phoned home. They're always in hot water, they lack taste, and they need dough.