Talking Tape. Rub your thumb nail along the ridges and listen to the message. Five different messages (‘congratulations’, ‘happy birthday’, etc) and 20 tapes to a pack for $19.58 (£9.99).
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? You have now!