A guy goes into a bar with his pet octopus and says "I bet $50 that no one here has a musical instrument that this octopus can't play."
The people in the bar look around and someone fetches an old guitar.
The octopus has a look, picks it up, tunes up the strings and starts playing the guitar. The octopus's owner pockets the fifty bucks.
Next guy comes up with a trumpet, octopus takes the horn, loosens up the keys, licks its lips and starts playing a 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 in a few moments later with a set of bagpipes under his arm. He puts them on the bar and says to the guy and his octopus, "Now, if your octopus can play that I'll give you a hundred dollars."
The octopus takes a look at the bagpipes, lifts it up, turns it over, has another look from another angle. Puzzled, the octopus's owner comes up and says "What are you fooling around for? Hurry up and play the damn thing!"
The octopus says "Play it? If I can figure out how to get its pyjamas off I'm gonna make love to it!"