There was an advertising gimmick I saw once that consisted of a plastic ribbon that you attached to a balloon. The ribbon had ridges on it that encoded an audi

There was an advertising gimmick I saw once that consisted of a plastic ribbon that you attached to a balloon. The ribbon had ridges on it that encoded an audio blurb. You pinched it at the top and pulled down, running your thumbnail over the ridges, and the balloon acted like the diaphragm of a speaker to play the audio.