Ariana Grande's Brother Reveals My Sister's Famous And So Am I

8/10/2014 7:38 AM PDT

Ariana Grande's brother revealed who he REALLY IS to his "Big Brother" castmates ... in the most bizarre and Grande-ose way possible.

Frankie Grande made the confession on the live feed -- that he's not only Ariana Grande's bro but also a BIG STAR in his own right and head ... and it wasn't received well.

His delivery makes him incredibly unlikeable ... but it's all part of a play to stay in the house and win $500K.

You gotta watch the video ... he's so famous it hurts ... or so he says.