I think men are like dogs while women are like cats.
A dog will hump pretty much any leg, but a cat is usually standoffish and it decides who it wants.
A dog is pretty straightforward - walk, eat, sleep, but you always wonder what a cat is thinking.
A dog will lay by your side but a cat will pounce out of no where.
A dog is grateful but cats believe they own you.
A dog is protective but a cat will watch with great interest while you are attacked.
A dog will pee anywhere but a cat needs privacy.
Maybe this analogy doesn't work on all levels but I do see a lot of similararities between males and dogs and cats and females. Can you think of more?