You begin by going around the circle. Each player chooses an animal to be. They need the action and the noise for the animal. For example, I'm usually the Elephant. I put my elbow to my nose and raise my arm, making trumpeting noises. Another exmaple is the cow (make horns on your head with your fingers and go moo).

To play the game, whoever starts makes their animal action and noise, then that of another player. That play then does their animal, followed by someone elses. And so on. Easy to learn, works best with 6-8 people and the faster the better. Won't get you too pissed though, but, like aliens, it's a big hit with the ladies.