God was just about done creating man, but he had two things left over in his bag and He couldn't quite decide how to split them between Adam and Eve. He thought He might just as well ask them. He told them one of the things He had left was a thing that would allow the owner to pee while standing up. "It's a very handy thing," God told them, "and I was wondering if either one of you had a preference for it."
Well, Adam jumped up and down and begged, "Oh, please give that to me! I'd love to be able to do that! It seems like just the sort of thing a man should have. Please! Pleeease! Give it to me!" On and on he went like an excited little boy. Eve just smiled and told God that if Adam really wanted it so badly, he could have it. So God gave Adam the thing that allowed him to pee standing up.
Adam was so excited he just started whizzing all over the place - first on the side of a rock, then he wrote his name in the sand, and then he tried to see if he could hit a stump ten feet away - laughing with delight all the while.
God and Eve watched him with amusement and then God said to Eve,
"Well, I guess you're kind of stuck with the last thing I have left."
"What's it called?" asked Eve.
"Brains," said God.