It's one of the most iconic hooks in all of Kanye West's catalog: "get down girl, go 'head, get down."

But now that refrain to West's huge 2005 #1 hit "Gold Digger" might cost him more than any groupie. According to TMZ, the family of David Pryor has filed suit against the rapper for allegedly sampling their dad's 1974 obscurity "Bumpin' Bus Stop" by his group Thunder & Lightning.

The suit by Trena Steward and Lorenzo Pryor claims that West lifted a 13-second bit of the song in which their dad, who died in 2006, says "get down" three times in an echo of West's recitation of the chorus, "Get down girl, go 'head, get down."

The pair, who each own one-quarter of the song, have asked the judge in the case to stop the sale of the song and provide them with "millions of dollars" in damages for the unlicensed sample. They also claim that the defendants named in the case have, "systematically and willfully refused to clear samples of the Plaintiffs' original, copyrighted work in order to gain a commercial profit and to avoid paying and crediting the author."

Allhiphop.com reported that the copyright/RICO lawsuit claims that West and various labels engaged in a 15-year "illegal copyright infringement scheme and criminal enterprise involving the unauthorized, willful sampling of plaintiffs original copyrighted music on a massive scale." In addition to West, the suit names Roc-a-Fella Records, Bad Boy Records, Stones Throw Records, Bomb Hip-Hop Records, Autumn Games, Activision, Caroline Distribution and The Island Def Jam Music Group. A spokesperson for West could not be reached for comment at press time.