The people in the bar look around and someone fetches out an old guitar. The octopus has a look, picks it up, tunes up the strings and starts playing. The octopus's owner pockets the fifty bucks.
Next guy comes up with a trumpet.
The octopus takes the horn, loosens up the keys, licks its lips and starts playing a fantastic jazz solo. The guy hands over another fifty bucks to the octopus's owner. The bar owner has been watching all this and disappears out back, coming back a few moments later with a set of bagpipes under his arm. The octopus takes a look at the bagpipes, lifts them up, turns them over, has another look from another angle.