I apologize for the language, but the song is called Poor Lil' Rich by 50 Cent.
Because of the excessive amount of N*gaaaaah!? in it, that's how I recognized the song.
What you hear them singing:
"I used to be a po' n*gaaaah!?"
"Now I'm a rich n*gaaaah!?"
I believe that's what I heard, I don't even like the Get Low song so I probably would have noticed it if it was there.