Well, you know who does mention Sir-mix-a-lot? Jonathan Coulton: he does explicitly state his song is a cover. He wrote a new melody, which the Glee people used

Well, you know who does mention Sir-mix-a-lot? Jonathan Coulton: he does explicitly state his song is a cover. He wrote a new melody, which the Glee people used but did not acknowledge. I'm not sure what Glee's position is, maybe they claim they are covering Sir-mix-a-lot and happened to make the same arrangement and write the same melody that Coulton did.