Birth of Wah Wah Pedal Vol. 6 is an albulm of Busman's.
Mr. Burns and Smithers give Busman the album with a copy of Jimi Hendrix The Feedback Sessions in return fro a bus ride to Garlicville. They did this after Busman commented on the uselessness of the money the two originally tried to pay with. 
- A Wah Wah Pedal is a pedal used to change the tone of a guitar.