I heard a similar story to Downeast Bob's. The punchline being that at least one of the pickers would have said, "That ain't the Earl did it"!

Q. What's the difference between a motorcycle and a banjo?

A. You can tune a motorcycle!

Q. What's the difference between a leaf rake and a banjo?

A. Your wife gets mad if the neighbors borrow the rake and don't return it.

Q. A guitar player and a banjo player both fall off a balcony at the top of a skyscraper at the same time. Which one will hit the ground first?

A. The guitar player. The banjo player will have to stop and retune at least once on the way down.

Actually, the term 'banjo tuning' is an oxymoron!