This dog doesn't need food. And whenever you're tired of playing with it, you can just hit the pause button. It's a new robot canine called AIBO, meaning "pal" in Japanese, which Sony will start selling June 1. About the size of a Chihuahua, the pooch has sensors in its paws and an antenna-like tail. A camera and sensor help the battery-powered dog detect objects and measure distance so it won't run into walls. AIBO enjoys getting petted and shows that it's happy by wagging its tail or flashing its green videocam eyes. It's smart enough to do a few tricks: sitting, begging. It can dance and play a tune. But AIBO is no mutt: It will sell for $2,500 on the Internet.