One places one of these between the fleshy parts of the
base of the thumb, like praying, cups the hands,
and blows through the membrane causing it to vibrate.
This is called playing the gum leaf.
Any Aussie worth his salt, can play the gum leaf.
Usually accompanied by a gentleman, with his mouth open
at certain degrees whilst tapping his skull
with a spoon, making the base "dock dock" noises.
As you can see, we have lots of cheap fun in Australia.