Say something funny,"" the reporters in Australia challenged Noel Coward. Without breaking stride, he replied, ""Kangaroo."" The sound of that word is about all this book has going for it. Two kangaroos in turtle neck sweaters are drawn in around what appears to be old mail order catalog pictures of Victorian, Edwardian and Grand Rapids Ghastly furniture and machinery. According to the rhyme, the pair can't bring themselves to throw anything away, just in case some of the outlandish things should some day come in handy. At just the point that they are about to share the Collier brothers' awful fate, they decide to give everything away. But--as soon as their house is clear, they start the ""just in case"" routine again. The rhyme is bright, but it does run on. The nudge to incipient collectors of the unusable is very slight and the old catalog pictures are, like the stuff of the era they came from, dark and heavy.