Playing the skin flute is actually a colourful
euphemism for the act of
fellatio.
You see, playing a real
flute involves applying your
mouth to one end while you
twiddle your
fingers up and down the shaft. Coincidentally, many of the
same skills are also involved when one attempts to play the
skin flute.
Note: While merely
twiddling your fingers along the
shaft is
good practice, it rarely produces the
proper sounds.