Riff Raff's Cousin Is High School Dunk Phenom, Calls Out LaVar Ball

Rap star Riff Raff ain't the only famous dude in his family -- his cousin is a high school basketball phenom who's gone viral for dunk videos ... and Raff says he's got real NBA talent.

The Neon Icon's younger cousin is Mac McClung -- a high school junior who's already gotten offers from 11 Division 1 college programs after averaging 29 points a game with 5.5. rebounds.

Plus, he dunked almost 40 TIMES last season -- which got him some serious Internet love.

Riff says Mac's the real deal -- with potential to ball with the best in the world.

"He just has the drive, you know what I mean? Same heart and drive, he has the NBA attitude. So with that, you can't coach that."

And, oh yeah, LaVar Ball -- Raff says his family's coming for you.