Gu Gu, a panda at the Beijing Zoo has attacked an intruding tourist for the third time. In the latest incident Gu Gu went ga ga after mauling a visitor who jumped a barrier to retrieve a child's toy. The tourist leapt over barrier surrounding the panda's outdoor exercise area to retrieve the toy dropped by his 5-year-old son, said a zoo spokeswoman. Gu Gu bit the intruder's legs and refused to let go until zookeepers pried his jaws open with tools. Gu Gu first made news in 2007 when he bit a drunken tourist who jumped into his pen and tried to hug him. The tourist retaliated by biting the panda in the back. In October, Gu Gu viciously bit a teenager who climbed into his exercise area out of curiosity.