A kangaroo kept getting out of his enclosure at the zoo. Knowing he could hop very high, they installed a new fence, 10 feet tall. The next morning, the kanagroo was found wandering around the grounds. The fence was increased to 20 feet with the same result. The next morning, as the workmen were adding another 10 feet onto the fence, the giraffe in the next enclosure asked the knagaroo, "How high do you think they'll go with that fence?" "Probably about a thousand feet, unless someone starts locking that damn gate at night!"