As many people as are interested can play, the more the merrier. A game for the more musically inclined. Low buzz factor.
One player takes a seat at the instrument. The other players drink unspecified amounts of beer from the bottles. The first player blows a note on his bottle, as if playing a flute. The person at the instrument has 3 tries to repeat the note with the instrument. If repeated correctly, the first player drinks. If the person never matches the note, he drinks three and passes his turn.