To "play" the recordings on the talking tapes, simply scratch it with your fingernails:
One method is to hold one end of the strip between your teeth. Then, when you run your nail along the strip you hear it talk, but no-one else does. Or you can stick one end of the strip to an inflated balloon or a paper cup using sticky tape. The balloon or cup acts as an amplifier, and you can then demonstrate it to anyone nearby. Never heard a balloon talk?
http://www.grand-illusions.com/acatalog/info_14.html - via Gizmodo