The episode: “Crash of the Moons,” ep. 417
The riff: Added by Servo after the main character is instructed to “Bring back the TR-14!”
The explanation: “The Boston Rag” is the name of a song from the second studio album by American rock band Steely Dan, “Countdown to Ecstasy.” As the lyrics say, “Bring back the Boston Rag, Tell all your buddies that it ain’t no drag.” The song wasn’t a particularly big success on its own, just another song on the album, which didn’t produce any big hits.
Novelty factor: I have never been a fan of Steely Dan, and thus did not recognize the reference.