the process of spreading the female buttcheeks and giving it oral pleasure with tongue and air blowing actions. All while giving the female pleasure in her vagina via the hands and fingers. These actions combined resemble playing the bag pipe. And since anal oral can be messy, the bag pipe is indeed dusty.
The male on female equivalent of a rusty trombone.
Savannah always craves the dusty bag pipe after she goes down on me.