We're not quite sure how to use these little whistles, but they were all quite the rage in 1948 when novelty companies everywhere where selling them by the gross. We only have a few, but they are all vintage and have never been used (at least that's what we're told). There are old store stock from a novelty company in Ohio.
An alternative name for these was tongue whistle, so we're guessing that the tongue must be used to make these work.
Two whistles are shown for illustration - plus, the inset shows the original box design.
Not for children.