Yung Joc has a seriously baller lifestyle -- but he can't pony up $2K for his 7-year-old son.

So says his baby mama, Fatimah Jester, who says he owes her the two grand and is suing the rapper to get it. She tells WSB-TV that he has "all kinds of cars" -- including Bentleys, Benzes, and Rovers -- but hasn't provided for his boy. A judge will hear the case Sept. 11.

A rep for Joc couldn't immediately be reached. Yung is also facing weapons charges.