I took the mouse and dangled it down through the hinged door on the top of the cage, swinging it gently around to get a good view. "Look at the two rodents becoming friends!" I exclaimed. My brother glared at me. "What are you doing?" "I want the rodents to meet each other." "That," he said, "is a gerbil. And that ," he added with an annoyed wave at the mouse in my hand, "is a digital pointing device."